Provided by: ghc_9.6.6-3_amd64 
NAME
ghc - the Glasgow Haskell Compiler
SYNOPSIS
ghc [option|filename]
ghci [option|filename]
DESCRIPTION
This manual page documents briefly the ghc and ghci commands. Note that ghci is not yet
available on all architectures. Extensive documentation is available in various other
formats including PDF <https://downloads.haskell.org/ghc/latest/docs/users_guide.pdf> and
HTML <https://downloads.haskell.org/ghc/latest/docs/html/>.
Each of GHC's command line options is classified as either static or dynamic. A static
flag may only be specified on the command line, whereas a dynamic flag may also be given
in an OPTIONS pragma in a source file or set from the GHCi command-line with :set .
As a rule of thumb, all the language options are dynamic, as are the warning options and
the debugging options.
The rest are static, with the notable exceptions of -v, -cpp, -fasm, -fvia-C, -fllvm, and
-#include. The OPTIONS sections lists the status of each flag.
Common suffixes of file names for Haskell are:
.hs Haskell source code; preprocess, compile
.lhs literate Haskell source; unlit, preprocess, compile
.hi Interface file; contains information about exported symbols
.hc intermediate C files
.⟨way⟩_o
object files for "way" ⟨way⟩; common ways are:
dyn dynamically-linked
p built with profiling
.⟨way⟩_hi
interface files for "way" ⟨way⟩; common ways are:
OPTIONS
Code generation
-dynamic-too -fasm -fllvm -fbyte-code -fbyte-code-and-object-code
-fexpose-internal-symbols -fexternal-dynamic-refs -fllvm -fasm -fno-code
-fobject-code -fPIC -fPIE -fprefer-byte-code -fwrite-if-simplified-core
-fwrite-interface -split-objs
Debugging the compiler
-dasm-lint -dcmm-lint -dcore-lint -ddump-asm -ddump-asm-conflicts
-ddump-asm-liveness -ddump-asm-native -ddump-asm-regalloc
-ddump-asm-regalloc-stages -ddump-asm-stats -ddump-bcos -ddump-c-backend
-ddump-call-arity -ddump-cfg-weights -ddump-cmm -ddump-cmm-caf -ddump-cmm-cbe
-ddump-cmm-cfg -ddump-cmm-cps -ddump-cmm-from-stg -ddump-cmm-info -ddump-cmm-opt
-ddump-cmm-proc -ddump-cmm-procmap -ddump-cmm-raw -ddump-cmm-sink -ddump-cmm-sp
-ddump-cmm-split -ddump-cmm-switch -ddump-cmm-thread-sanitizer -ddump-cmm-verbose
-ddump-cmm-verbose-by-proc -ddump-core-stats -ddump-cpr-signatures -ddump-cpranal
-ddump-cs-trace -ddump-cse -ddump-debug -ddump-deriv -ddump-ds -ddump-ds-preopt
-ddump-ec-trace -ddump-exitify -ddump-faststrings -ddump-file-prefix=⟨str⟩
-ddump-foreign -ddump-hie -ddump-hpc -ddump-if-trace -ddump-inlinings -ddump-js
-ddump-json -ddump-late-cc -ddump-llvm -ddump-mod-map -ddump-occur-anal
-ddump-opt-cmm -ddump-parsed -ddump-parsed-ast -ddump-prep -ddump-rn -ddump-rn-ast
-ddump-rn-stats -ddump-rn-trace -ddump-rtti -ddump-rule-firings
-ddump-rule-rewrites -ddump-rules -ddump-simpl -ddump-simpl-iterations
-ddump-simpl-stats -ddump-simpl-trace -ddump-spec -ddump-splices -ddump-stg
-ddump-stg-cg -ddump-stg-final -ddump-stg-from-core -ddump-stg-tags
-ddump-stg-unarised -ddump-str-signatures -ddump-stranal -ddump-tc -ddump-tc-ast
-ddump-tc-trace -ddump-ticked -ddump-timings -ddump-to-file -ddump-types
-ddump-verbose-inlinings -ddump-view-pattern-commoning -ddump-worker-wrapper
-dfaststring-stats -dhex-word-literals -dinitial-unique=⟨s⟩ -dinline-check=⟨str⟩
-dipe-stats -dkeep-comments -dlinear-core-lint -dlint -dno-debug-output
-ddebug-output -dno-typeable-binds -dppr-case-as-let -dppr-cols=⟨n⟩ -dppr-debug
-dppr-user-length -drule-check=⟨str⟩ -dshow-passes -dstg-lint -dsuppress-all
-dsuppress-coercion-types -dsuppress-coercions -dsuppress-core-sizes
-dsuppress-idinfo -dsuppress-module-prefixes -dsuppress-stg-free-vars
-dsuppress-stg-reps -dsuppress-ticks -dsuppress-timestamps
-dsuppress-type-applications -dsuppress-type-signatures -dsuppress-unfoldings
-dsuppress-uniques -dsuppress-var-kinds -dtag-inference-checks -dth-dec-file
-dunique-increment=⟨i⟩ -dverbose-core2core -dverbose-stg2stg
-falignment-sanitisation -fcatch-nonexhaustive-cases -fcheck-prim-bounds
-fcmm-thread-sanitizer -fdistinct-constructor-tables -fdump-with-ways
-finfo-table-map -finfo-table-map-with-fallback -fno-info-table-map-with-fallback
-finfo-table-map-with-stack -fno-info-table-map-with-stack
-fllvm-fill-undef-with-garbage -fno-info-table-map-with-fallback
-finfo-table-map-with-fallback -fno-info-table-map-with-stack
-finfo-table-map-with-stack -fproc-alignment -g -g⟨n⟩
C pre-processor
-cpp -D⟨symbol⟩[=⟨value⟩] -U⟨symbol⟩ -I⟨dir⟩ -U⟨symbol⟩
Finding imports
-i -i⟨dir⟩[:⟨dir⟩]*
Interactive mode
-fbreak-on-error -fno-break-on-error -fbreak-on-exception -fno-break-on-exception
-fghci-hist-size=⟨n⟩ -fghci-leak-check -fno-ghci-leak-check
-fimplicit-import-qualified -fno-implicit-import-qualified -flocal-ghci-history
-fno-local-ghci-history -fno-it -fno-no-it -fprint-bind-result
-fno-print-bind-result -fprint-evld-with-show -fshow-loaded-modules -ghci-script
-ignore-dot-ghci -no-ignore-dot-ghci -interactive-print ⟨name⟩
Interface files
--show-iface ⟨file⟩ -ddump-hi -ddump-hi-diffs -ddump-minimal-imports
Keeping intermediate files
-keep-hc-file -keep-hc-files -keep-hi-files -no-keep-hi-files -keep-hscpp-file
-keep-hscpp-files -keep-llvm-file -keep-llvm-files -keep-o-files -no-keep-o-files
-keep-s-file -keep-s-files -keep-tmp-files
Language options
-XAllowAmbiguousTypes -XApplicativeDo -XArrows -XBangPatterns -XBinaryLiterals
-XBlockArguments -XCApiFFI -XConstrainedClassMethods -XConstraintKinds -XCPP
-XCUSKs -XDataKinds -XDatatypeContexts -XDeepSubsumption -XDefaultSignatures
-XDeriveAnyClass -XDeriveDataTypeable -XDeriveFoldable -XDeriveFunctor
-XDeriveGeneric -XDeriveLift -XDeriveTraversable -XDerivingStrategies -XDerivingVia
-XDisambiguateRecordFields -XDuplicateRecordFields -XEmptyCase -XEmptyDataDecls
-XEmptyDataDeriving -XExistentialQuantification -XExplicitForAll
-XExplicitNamespaces -XExtendedDefaultRules -XFieldSelectors -XFlexibleContexts
-XFlexibleInstances -XForeignFunctionInterface -XFunctionalDependencies -XGADTs
-XGADTSyntax -XGeneralisedNewtypeDeriving -XGeneralizedNewtypeDeriving -XGHC2021
-XGHCForeignImportPrim -XHaskell2010 -XHaskell98 -XHexFloatLiterals
-XImplicitParams -XImportQualifiedPost -XImpredicativeTypes -XIncoherentInstances
-XInstanceSigs -XInterruptibleFFI -XKindSignatures -XLambdaCase -XLexicalNegation
-XLiberalTypeSynonyms -XLinearTypes -XMagicHash -XMonadComprehensions
-XMonoLocalBinds -XMultiParamTypeClasses -XMultiWayIf -XNamedFieldPuns
-XNamedWildCards -XNegativeLiterals -XNoImplicitPrelude -XNoMonomorphismRestriction
-XNondecreasingIndentation -XNoPatternGuards -XNoTraditionalRecordSyntax
-XNPlusKPatterns -XNullaryTypeClasses -XNumDecimals -XNumericUnderscores
-XOverlappingInstances -XOverloadedLabels -XOverloadedLists -XOverloadedRecordDot
-XOverloadedRecordUpdate -XOverloadedStrings -XPackageImports -XParallelListComp
-XPartialTypeSignatures -XPatternSynonyms -XPolyKinds -XPostfixOperators
-XQualifiedDo -XQuantifiedConstraints -XQuasiQuotes -XRank2Types -XRankNTypes
-XRebindableSyntax -XRecordWildCards -XRecursiveDo -XRoleAnnotations -XSafe
-XScopedTypeVariables -XStandaloneDeriving -XStandaloneKindSignatures -XStarIsType
-XStaticPointers -XStrict -XStrictData -XTemplateHaskell -XTemplateHaskellQuotes
-XTransformListComp -XTrustworthy -XTupleSections -XTypeApplications -XTypeData
-XTypeFamilies -XTypeFamilyDependencies -XTypeInType -XTypeOperators
-XTypeSynonymInstances -XUnboxedSums -XUnboxedTuples -XUndecidableInstances
-XUndecidableSuperClasses -XUnicodeSyntax -XUnliftedDatatypes -XUnliftedFFITypes
-XUnliftedNewtypes -XUnsafe -XViewPatterns
Linking options
-c -debug -dylib-install-name ⟨path⟩ -dynamic -dynload -eventlog -fcompact-unwind
-fkeep-cafs -flink-rts -fno-embed-manifest -fno-gen-manifest -fno-shared-implib
-framework ⟨name⟩ -framework-path ⟨dir⟩ -fsplit-sections -split-sections
-fno-split-sections -fuse-rpaths -fwhole-archive-hs-libs -L ⟨dir⟩ -l ⟨lib⟩ -main-is
⟨thing⟩ -no-hs-main -no-pie -pie -no-rtsopts-suggestions -package ⟨name⟩ -pie
-no-pie -rdynamic -rtsopts[=⟨none|some|all|ignore|ignoreAll⟩] -shared -static
-staticlib -threaded -with-rtsopts=⟨opts⟩
Miscellaneous options
-ddump-mod-cycles -fexternal-interpreter -ffamily-application-cache
-fno-family-application-cache -fglasgow-exts -fno-glasgow-exts -fno-safe-haskell
-ghcversion-file ⟨path to ghcversion.h⟩ -H ⟨size⟩ -hidden-module ⟨module name⟩
-j[⟨n⟩] -reexported-module ⟨module name⟩ -this-package-name ⟨unit-id⟩ -unit
@⟨filename⟩ -working-dir ⟨dir⟩
Modes of operation
--frontend ⟨module⟩ --help -? --info --interactive --make --numeric-version
--print-booter-version --print-build-platform --print-c-compiler-flags
--print-c-compiler-link-flags --print-debug-on --print-global-package-db
--print-have-interpreter --print-have-native-code-generator --print-host-platform
--print-ld-flags --print-leading-underscore --print-libdir
--print-object-splitting-supported --print-project-git-commit-id
--print-project-version --print-rts-ways --print-stage --print-support-smp
--print-tables-next-to-code --print-target-platform --print-unregisterised --run
⟨file⟩ --show-iface ⟨file⟩ --show-options --supported-extensions
--supported-languages --version -V -e ⟨expr⟩ -M -shared
Individual optimizations
-fasm-shortcutting -fno-asm-shortcutting -fbinary-blob-threshold=⟨n⟩
-fblock-layout-cfg -fno-block-layout-cfg -fblock-layout-weightless
-fno-block-layout-weightless -fblock-layout-weights -fcall-arity -fno-call-arity
-fcase-folding -fno-case-folding -fcase-merge -fno-case-merge -fcmm-control-flow
-fno-cmm-control-flow -fcmm-elim-common-blocks -fno-cmm-elim-common-blocks
-fcmm-sink -fno-cmm-sink -fcmm-static-pred -fno-cmm-static-pred
-fcore-constant-folding -fno-core-constant-folding -fcpr-anal -fno-cpr-anal
-fcross-module-specialise -fno-cross-module-specialise -fcse -fno-cse -fdicts-cheap
-fno-dicts-cheap -fdicts-strict -fno-dicts-strict -fdmd-tx-dict-sel
-fno-dmd-tx-dict-sel -fdmd-unbox-width=⟨n⟩ -fdo-eta-reduction -fno-do-eta-reduction
-fdo-lambda-eta-expansion -fno-do-lambda-eta-expansion -feager-blackholing
-fenable-rewrite-rules -fno-enable-rewrite-rules -fexcess-precision
-fno-excess-precision -fexitification -fno-exitification -fexpose-all-unfoldings
-fno-expose-all-unfoldings -ffloat-in -fno-float-in -ffull-laziness
-fno-full-laziness -ffun-to-thunk -fno-fun-to-thunk -fignore-asserts
-fno-ignore-asserts -fignore-interface-pragmas -fno-ignore-interface-pragmas
-finline-generics -fno-inline-generics -finline-generics-aggressively
-fno-inline-generics-aggressively -flate-dmd-anal -fno-late-dmd-anal
-flate-specialise -fno-late-specialise -fliberate-case -fno-liberate-case
-fliberate-case-threshold=⟨n⟩ -fno-liberate-case-threshold
-fllvm-pass-vectors-in-regs -flocal-float-out -fno-local-float-out
-flocal-float-out-top-level -fno-local-float-out-top-level -floopification
-fno-loopification -fmax-inline-alloc-size=⟨n⟩ -fmax-inline-memcpy-insns=⟨n⟩
-fmax-inline-memset-insns=⟨n⟩ -fmax-simplifier-iterations=⟨n⟩
-fmax-uncovered-patterns=⟨n⟩ -fmax-worker-args=⟨n⟩ -fno-opt-coercion
-fno-pre-inlining -fno-state-hack -fomit-interface-pragmas
-fno-omit-interface-pragmas -fomit-yields -fno-omit-yields -foptimal-applicative-do
-fno-optimal-applicative-do -fpedantic-bottoms -fno-pedantic-bottoms
-fpolymorphic-specialisation -fno-polymorphic-specialisation -fregs-graph
-fno-regs-graph -fregs-iterative -fno-regs-iterative -fsimpl-tick-factor=⟨n⟩
-fsimplifier-phases=⟨n⟩ -fsolve-constant-dicts -fno-solve-constant-dicts
-fspec-constr -fno-spec-constr -fspec-constr-count=⟨n⟩ -fno-spec-constr-count
-fspec-constr-keen -fno-spec-constr-keen -fspec-constr-threshold=⟨n⟩
-fno-spec-constr-threshold -fspecialise -fno-specialise -fspecialise-aggressively
-fno-specialise-aggressively -fstatic-argument-transformation
-fno-static-argument-transformation -fstg-cse -fno-stg-cse -fstg-lift-lams
-fno-stg-lift-lams -fstg-lift-lams-known -fno-stg-lift-lams-known
-fstg-lift-lams-non-rec-args -fstg-lift-lams-non-rec-args-any
-fstg-lift-lams-rec-args -fstg-lift-lams-rec-args-any -fstrictness -fno-strictness
-fstrictness-before=⟨n⟩ -funbox-small-strict-fields -fno-unbox-small-strict-fields
-funbox-strict-fields -fno-unbox-strict-fields -funfolding-case-scaling=⟨n⟩
-funfolding-case-threshold=⟨n⟩ -funfolding-creation-threshold=⟨n⟩
-funfolding-dict-discount=⟨n⟩ -funfolding-fun-discount=⟨n⟩
-funfolding-keeness-factor=⟨n⟩ -funfolding-use-threshold=⟨n⟩ -fworker-wrapper
-fworker-wrapper-cbv
Optimization levels
-O -O1 -O0 -O0 -O2 -O0 -O⟨n⟩ -O0
Package options
-clear-package-db -distrust ⟨pkg⟩ -distrust-all-packages -fpackage-trust
-global-package-db -hide-all-packages -hide-package ⟨pkg⟩ -ignore-package ⟨pkg⟩
-no-auto-link-packages -no-global-package-db -no-user-package-db -package ⟨pkg⟩
-package-db ⟨file⟩ -package-env ⟨file⟩|⟨name⟩ -package-id ⟨unit-id⟩ -this-unit-id
⟨unit-id⟩ -trust ⟨pkg⟩ -user-package-db
Phases of compilation
--merge-objs -C -c -E -F -S -x ⟨suffix⟩
Overriding external programs
-pgma ⟨cmd⟩ -pgmc ⟨cmd⟩ -pgmcxx ⟨cmd⟩ -pgmdll ⟨cmd⟩ -pgmF ⟨cmd⟩ -pgmi ⟨cmd⟩
-pgminstall_name_tool ⟨cmd⟩ -pgmL ⟨cmd⟩ -pgml ⟨cmd⟩ -pgmlc ⟨cmd⟩ -pgmlm ⟨cmd⟩
-pgmlo ⟨cmd⟩ -pgmotool ⟨cmd⟩ -pgmP ⟨cmd⟩ -pgms ⟨cmd⟩ -pgmwindres ⟨cmd⟩
Phase-specific options
-opta ⟨option⟩ -optc ⟨option⟩ -optcxx ⟨option⟩ -optdll ⟨option⟩ -optF ⟨option⟩
-opti ⟨option⟩ -optL ⟨option⟩ -optl ⟨option⟩ -optlc ⟨option⟩ -optlm ⟨option⟩ -optlo
⟨option⟩ -optP ⟨option⟩ -optwindres ⟨option⟩ -pgmc-supports-no-pie
-pgml-supports-no-pie
Platform-specific options
-mavx -mavx2 -mavx512cd -mavx512er -mavx512f -mavx512pf -mbmi -mbmi2 -msse -msse2
-msse3 -msse4 -msse4.2
Compiler plugins
-fclear-plugins -fplugin-library=⟨file-path⟩;⟨unit-id⟩;⟨module⟩;⟨args⟩
-fplugin-opt=⟨module⟩:⟨args⟩ -fplugin-trustworthy -fplugin=⟨module⟩
-hide-all-plugin-packages -plugin-package ⟨pkg⟩ -plugin-package-id ⟨pkg-id⟩
Profiling
-auto -auto-all -caf-all -fno-prof-count-entries -fprof-count-entries -fprof-auto
-fno-prof-auto -fprof-auto-calls -fno-prof-auto -fprof-auto-exported -fno-prof-auto
-fprof-auto-top -fno-prof-auto -fprof-cafs -fno-prof-cafs -fprof-callers=⟨name⟩
-fprof-late -fno-prof-late -fprof-late-inline -fno-prof-late-inline -fprof-manual
-fno-prof-manual -no-auto -no-auto-all -no-caf-all -prof -ticky -ticky-allocd
-ticky-ap-thunk -ticky-dyn-thunk -ticky-LNE -ticky-tag-checks
Program coverage
-fhpc -hpcdir⟨dir⟩
Recompilation checking
-exclude-module=⟨file⟩ -fforce-recomp -fno-force-recomp -fignore-hpc-changes
-fno-ignore-hpc-changes -fignore-optim-changes -fno-ignore-optim-changes
-include-cpp-deps -include-pkg-deps
Redirecting output
-dep-makefile ⟨file⟩ -dep-suffix ⟨suffix⟩ -dumpdir ⟨dir⟩ -dynhisuf ⟨suffix⟩ -dyno
⟨file⟩ -dynohi ⟨file⟩ -dynosuf ⟨suffix⟩ -hcsuf ⟨suffix⟩ -hidir ⟨dir⟩ -hiedir ⟨dir⟩
-hiesuf ⟨suffix⟩ -hisuf ⟨suffix⟩ -o ⟨file⟩ -odir ⟨dir⟩ -ohi ⟨file⟩ -osuf ⟨suffix⟩
-outputdir ⟨dir⟩ -stubdir ⟨dir⟩
Temporary files
-tmpdir ⟨dir⟩
Verbosity options
-fabstract-refinement-hole-fits -fno-abstract-refinement-hole-fits
-fdefer-diagnostics -fdiagnostics-color=⟨always|auto|never⟩
-fdiagnostics-show-caret -fno-diagnostics-show-caret -ferror-spans
-fhide-source-paths -fkeep-going -fmax-refinement-hole-fits=⟨n⟩
-fno-max-refinement-hole-fits -fmax-relevant-binds=⟨n⟩ -fno-max-relevant-binds
-fmax-valid-hole-fits=⟨n⟩ -fno-max-valid-hole-fits -fno-show-valid-hole-fits
-fno-sort-valid-hole-fits -fsort-valid-hole-fits -fprint-axiom-incomps
-fno-print-axiom-incomps -fprint-equality-relations -fno-print-equality-relations
-fprint-expanded-synonyms -fno-print-expanded-synonyms -fprint-explicit-coercions
-fno-print-explicit-coercions -fprint-explicit-foralls -fno-print-explicit-foralls
-fprint-explicit-kinds -fno-print-explicit-kinds -fprint-explicit-runtime-reps
-fno-print-explicit-runtime-reps -fprint-potential-instances
-fno-print-potential-instances -fprint-redundant-promotion-ticks
-fno-print-redundant-promotion-ticks -fprint-typechecker-elaboration
-fno-print-typechecker-elaboration -fprint-unicode-syntax -fno-print-unicode-syntax
-frefinement-level-hole-fits=⟨n⟩ -fno-refinement-level-hole-fits -freverse-errors
-fno-reverse-errors -fshow-docs-of-hole-fits -fno-show-docs-of-hole-fits
-fshow-error-context -fno-show-error-context -fshow-hole-constraints
-fshow-hole-matches-of-hole-fits -fno-show-hole-matches-of-hole-fits
-fshow-provenance-of-hole-fits -fno-show-provenance-of-hole-fits
-fshow-type-app-of-hole-fits -fno-show-type-app-of-hole-fits
-fshow-type-app-vars-of-hole-fits -fno-show-type-app-vars-of-hole-fits
-fshow-type-of-hole-fits -fno-show-type-of-hole-fits -fsort-by-size-hole-fits
-fno-sort-by-size-hole-fits -fsort-by-subsumption-hole-fits
-fno-sort-by-subsumption-hole-fits -funclutter-valid-hole-fits -Rghc-timing -v
-v⟨n⟩
Warnings
-fdefer-out-of-scope-variables -fno-defer-out-of-scope-variables
-fdefer-type-errors -fno-defer-type-errors -fdefer-typed-holes
-fno-defer-typed-holes -fenable-th-splice-warnings -fno-enable-th-splice-warnings
-fhelpful-errors -fno-helpful-errors -fmax-pmcheck-models=⟨n⟩ -fshow-warning-groups
-fno-show-warning-groups -fvia-C -W -w -w -Wall -w -Wall-missed-specialisations
-Wno-all-missed-specialisations -Wall-missed-specializations
-Wno-all-missed-specializations -Wambiguous-fields -Wauto-orphans -Wcompat
-Wno-compat -Wcompat-unqualified-imports -Wno-compat-unqualified-imports
-Wcpp-undef -Wdefault -Wdeferred-out-of-scope-variables
-Wno-deferred-out-of-scope-variables -Wdeferred-type-errors
-Wno-deferred-type-errors -Wdeprecated-flags -Wno-deprecated-flags -Wdeprecations
-Wno-deprecations -Wderiving-defaults -Wno-deriving-defaults -Wderiving-typeable
-Wno-deriving-typeable -Wdodgy-exports -Wno-dodgy-exports -Wdodgy-foreign-imports
-Wno-dodgy-foreign-imports -Wdodgy-imports -Wno-dodgy-imports
-Wduplicate-constraints -Wno-duplicate-constraints -Wduplicate-exports
-Wno-duplicate-exports -Wempty-enumerations -Wno-empty-enumerations -Werror -Wwarn
-Weverything -Wextra -w -Wforall-identifier -Wno-forall-identifier
-Wgadt-mono-local-binds -Wno-gadt-mono-local-binds -Whi-shadowing -Wno-hi-shadowing
-Widentities -Wno-identities -Wimplicit-kind-vars -Wno-implicit-kind-vars
-Wimplicit-lift -Wno-implicit-lift -Wimplicit-prelude -Wno-implicit-prelude
-Winaccessible-code -Wno-inaccessible-code -Wincomplete-patterns
-Wno-incomplete-patterns -Wincomplete-record-updates -Wno-incomplete-record-updates
-Wincomplete-uni-patterns -Wno-incomplete-uni-patterns -Winferred-safe-imports
-Wno-inferred-safe-imports -Winline-rule-shadowing -Wno-inline-rule-shadowing
-Winvalid-haddock -Wno-invalid-haddock -Wloopy-superclass-solve
-Wno-loopy-superclass-solve -Wmisplaced-pragmas -Wno-misplaced-pragmas
-Wmissed-extra-shared-lib -Wno-missed-extra-shared-lib -Wmissed-specialisations
-Wno-missed-specialisations -Wmissed-specializations -Wno-missed-specializations
-Wmissing-deriving-strategies -Wno-missing-deriving-strategies
-Wmissing-export-lists -Wno-missing-export-lists
-Wmissing-exported-pattern-synonym-signatures
-Wno-missing-exported-pattern-synonym-signatures -Wmissing-exported-signatures
-Wno-missing-exported-signatures -Wmissing-exported-sigs -Wno-missing-exported-sigs
-Wmissing-fields -Wno-missing-fields -Wmissing-home-modules
-Wno-missing-home-modules -Wmissing-import-lists -Wno-missing-import-lists
-Wmissing-kind-signatures -Wno-missing-kind-signatures -Wmissing-local-signatures
-Wno-missing-local-signatures -Wmissing-local-sigs -Wno-missing-local-sigs
-Wmissing-methods -Wno-missing-methods -Wmissing-monadfail-instances
-Wno-missing-monadfail-instances -Wmissing-pattern-synonym-signatures
-Wno-missing-pattern-synonym-signatures -Wmissing-safe-haskell-mode
-Wno-missing-safe-haskell-mode -Wmissing-signatures -Wno-missing-signatures
-Wmissing-space-after-bang -Wmonomorphism-restriction -Wno-monomorphism-restriction
-Wname-shadowing -Wno-name-shadowing -Wno-compat -Wcompat
-Wnoncanonical-monad-instances -Wno-noncanonical-monad-instances
-Wnoncanonical-monadfail-instances -Wno-noncanonical-monadfail-instances
-Wnoncanonical-monoid-instances -Wno-noncanonical-monoid-instances -Wnot
-Woperator-whitespace -Wno-operator-whitespace -Woperator-whitespace-ext-conflict
-Wno-operator-whitespace-ext-conflict -Worphans -Wno-orphans -Woverflowed-literals
-Wno-overflowed-literals -Woverlapping-patterns -Wno-overlapping-patterns
-Wpartial-fields -Wno-partial-fields -Wpartial-type-signatures
-Wno-partial-type-signatures -Wprepositive-qualified-module
-Wno-prepositive-qualified-module -Wredundant-bang-patterns
-Wno-redundant-bang-patterns -Wredundant-constraints -Wno-redundant-constraints
-Wredundant-record-wildcards -Wno-redundant-record-wildcards
-Wredundant-strictness-flags -Wno-redundant-strictness-flags -Wsafe -Wno-safe
-Wsemigroup -Wno-semigroup -Wsimplifiable-class-constraints
-Wno-simplifiable-class-constraints -Wstar-binder -Wno-star-binder -Wstar-is-type
-Wno-star-is-type -Wtabs -Wno-tabs -Wtrustworthy-safe -Wno-safe -Wtype-defaults
-Wno-type-defaults -Wtype-equality-out-of-scope -Wno-type-equality-out-of-scope
-Wtype-equality-requires-operators -Wno-type-equality-requires-operators
-Wtyped-holes -Wno-typed-holes -Wunbanged-strict-patterns
-Wno-unbanged-strict-patterns -Wunicode-bidirectional-format-characters
-Wunrecognised-pragmas -Wno-unrecognised-pragmas -Wunrecognised-warning-flags
-Wno-unrecognised-warning-flags -Wunsafe -Wno-unsafe
-Wunsupported-calling-conventions -Wno-unsupported-calling-conventions
-Wunsupported-llvm-version -Wno-monomorphism-restriction
-Wunticked-promoted-constructors -Wno-unticked-promoted-constructors -Wunused-binds
-Wno-unused-binds -Wunused-do-bind -Wno-unused-do-bind -Wunused-foralls
-Wno-unused-foralls -Wunused-imports -Wno-unused-imports -Wunused-local-binds
-Wno-unused-local-binds -Wunused-matches -Wno-unused-matches -Wunused-packages
-Wno-unused-packages -Wunused-pattern-binds -Wno-unused-pattern-binds
-Wunused-record-wildcards -Wno-unused-record-wildcards -Wunused-top-binds
-Wno-unused-top-binds -Wunused-type-patterns -Wno-unused-type-patterns -Wwarn
-Werror -Wwarnings-deprecations -Wno-warnings-deprecations -Wwrong-do-bind
-Wno-wrong-do-bind
Code generation
-dynamic-too
Build dynamic object files as well as static object files during compilation
-fasm Use the native code generator
-fbyte-code
Generate byte-code
-fbyte-code-and-object-code
Generate object code and byte-code
-fexpose-internal-symbols
Produce symbols for all functions, including internal functions.
-fexternal-dynamic-refs
Generate code for linking against dynamic libraries
-fllvm Compile using the LLVM code generator
-fno-code
Omit code generation
-fobject-code
Generate object code
-fPIC Generate position-independent code (where available)
-fPIE Generate code for a position-independent executable (where available)
-fprefer-byte-code
Use byte-code if it is available to evaluate TH splices
-fwrite-if-simplified-core
Write an interface file containing the simplified core of the module.
-fwrite-interface
Always write interface files
-split-objs
Split generated object files into smaller files
Debugging the compiler
-dasm-lint
ASM pass sanity checking
-dcmm-lint
C-\- pass sanity checking
-dcore-lint
Turn on internal sanity checking
-ddump-asm
Dump final assembly
-ddump-asm-conflicts
Dump register conflicts from the register allocator.
-ddump-asm-liveness
Dump assembly augmented with register liveness
-ddump-asm-native
Dump initial assembly
-ddump-asm-regalloc
Dump the result of register allocation
-ddump-asm-regalloc-stages
Dump the build/spill stages of the -fregs-graph register allocator.
-ddump-asm-stats
Dump statistics from the register allocator.
-ddump-bcos
Dump interpreter byte code
-ddump-c-backend
Dump C code produced by the C (unregisterised) backend.
-ddump-call-arity
Dump output of the call arity analysis pass.
-ddump-cfg-weights
Dump the assumed weights of the CFG.
-ddump-cmm
Dump the final C-\- output
-ddump-cmm-caf
Dump the results of the C-\- CAF analysis pass.
-ddump-cmm-cbe
Dump the results of common block elimination
-ddump-cmm-cfg
Dump the results of the C-\- control flow optimisation pass.
-ddump-cmm-cps
Dump the results of the CPS pass
-ddump-cmm-from-stg
Dump STG-to-C-\- output
-ddump-cmm-info
Dump the results of the C-\- info table augmentation pass.
-ddump-cmm-opt
Dump the results of C-\- to C-\- optimising passes
-ddump-cmm-proc
Dump the results of proc-point analysis
-ddump-cmm-procmap
Dump the results of the C-\- proc-point map pass.
-ddump-cmm-raw
Dump raw C-\-
-ddump-cmm-sink
Dump the results of the C-\- sinking pass.
-ddump-cmm-sp
Dump the results of the C-\- stack layout pass.
-ddump-cmm-split
Dump the results of the C-\- proc-point splitting pass.
-ddump-cmm-switch
Dump the results of switch lowering passes
-ddump-cmm-thread-sanitizer
Dump the results of the C-\- ThreadSanitizer elaboration pass.
-ddump-cmm-verbose
Write output from main C-\- pipeline passes to files
-ddump-cmm-verbose-by-proc
Show output from main C-\- pipeline passes (grouped by proc)
-ddump-core-stats
Print a one-line summary of the size of the Core program at the end of the
optimisation pipeline
-ddump-cpr-signatures
Dump CPR signatures
-ddump-cpranal
Dump CPR analysis output
-ddump-cs-trace
Trace constraint solver
-ddump-cse
Dump CSE output
-ddump-debug
Dump generated DWARF debug information
-ddump-deriv
Dump deriving output
-ddump-ds
Dump desugarer output.
-ddump-ec-trace
Trace exhaustiveness checker
-ddump-exitify
Dump output of the exitification pass.
-ddump-faststrings
Dump the whole FastString table when finished
-ddump-file-prefix=⟨str⟩
Set the prefix of the filenames used for debugging output.
-ddump-foreign
Dump foreign export stubs
-ddump-hie
Dump the hie file syntax tree
-ddump-hpc
An alias for -ddump-ticked.
-ddump-if-trace
Trace interface files
-ddump-inlinings
Dump inlinings performed by the simplifier.
-ddump-js
Dump final JavaScript code
-ddump-json
Dump error messages as JSON documents
-ddump-late-cc
Dump core with late cost centres added
-ddump-llvm
Dump LLVM intermediate code.
-ddump-mod-map
Dump the state of the module mapping database.
-ddump-occur-anal
Dump occurrence analysis output
-ddump-opt-cmm
Dump the results of C-\- to C-\- optimising passes
-ddump-parsed
Dump parse tree
-ddump-parsed-ast
Dump parser output as a syntax tree
-ddump-prep
Dump prepared core
-ddump-rn
Dump renamer output
-ddump-rn-ast
Dump renamer output as a syntax tree
-ddump-rn-stats
Renamer stats
-ddump-rn-trace
Trace renamer
-ddump-rtti
Trace runtime type inference
-ddump-rule-firings
Dump rule firing info
-ddump-rule-rewrites
Dump detailed rule firing info
-ddump-rules
Dump rewrite rules
-ddump-simpl
Dump final simplifier output
-ddump-simpl-iterations
Dump output from each simplifier iteration
-ddump-simpl-stats
Dump simplifier stats
-ddump-simpl-trace
Dump trace messages in simplifier
-ddump-spec
Dump specialiser output
-ddump-splices
Dump TH spliced expressions, and what they evaluate to
-ddump-stg
(deprecated) Alias for -ddump-stg-from-core
-ddump-stg-cg
Show output after Stg2Stg
-ddump-stg-final
Show output of last STG pass.
-ddump-stg-from-core
Show CoreToStg output
-ddump-stg-tags
Show output of the tag inference pass.
-ddump-stg-unarised
Show unarised STG
-ddump-str-signatures
Dump top-level demand signatures
-ddump-stranal
Dump demand analysis output
-ddump-tc
Dump typechecker output
-ddump-tc-ast
Dump typechecker output as a syntax tree
-ddump-tc-trace
Trace typechecker
-ddump-ticked
Dump the code instrumented by HPC (Observing Code Coverage).
-ddump-timings
Dump per-pass timing and allocation statistics
-ddump-to-file
Dump to files instead of stdout
-ddump-types
Dump type signatures
-ddump-verbose-inlinings
Dump all considered inlinings
-ddump-view-pattern-commoning
Dump commoned view patterns
-ddump-worker-wrapper
Dump worker-wrapper output
-dfaststring-stats
Show statistics for fast string usage when finished
-dhex-word-literals
Print values of type Word# in hexadecimal.
-dinitial-unique=⟨s⟩
Start UniqSupply allocation from ⟨s⟩.
-dinline-check=⟨str⟩
Dump information about inlining decisions
-dipe-stats
Show statistics about IPE information
-dkeep-comments
Include comments in the parser. Useful in combination with -ddump-parsed-ast.
-dlinear-core-lint
Turn on internal sanity checking
-dlint Enable several common internal sanity checkers
-dno-debug-output
Suppress unsolicited debugging output
-dno-typeable-binds
Don't generate bindings for Typeable methods
-dppr-case-as-let
Print single alternative case expressions as strict lets.
-dppr-cols=⟨n⟩
Set the width of debugging output. For example -dppr-cols200
-dppr-debug
Turn on debug printing (more verbose)
-dppr-user-length
Set the depth for printing expressions in error msgs
-drule-check=⟨str⟩
Dump information about potential rule application
-dshow-passes
Print out each pass name as it happens
-dstg-lint
STG pass sanity checking
-dsuppress-all
In dumps, suppress everything (except for uniques) that is suppressible.
-dsuppress-coercion-types
Suppress the printing of coercion types in Core dumps to make them shorter
-dsuppress-coercions
Suppress the printing of coercions in Core dumps to make them shorter
-dsuppress-core-sizes
Suppress the printing of core size stats per binding (since 9.4)
-dsuppress-idinfo
Suppress extended information about identifiers where they are bound
-dsuppress-module-prefixes
Suppress the printing of module qualification prefixes
-dsuppress-stg-free-vars
Suppress the printing of closure free variable lists in STG output
-dsuppress-stg-reps
Suppress rep annotations on STG args.
-dsuppress-ticks
Suppress "ticks" in the pretty-printer output.
-dsuppress-timestamps
Suppress timestamps in dumps
-dsuppress-type-applications
Suppress type applications
-dsuppress-type-signatures
Suppress type signatures
-dsuppress-unfoldings
Suppress the printing of the stable unfolding of a variable at its binding site
-dsuppress-uniques
Suppress the printing of uniques in debug output (easier to use diff)
-dsuppress-var-kinds
Suppress the printing of variable kinds
-dtag-inference-checks
Affirm tag inference results are correct at runtime.
-dth-dec-file
Dump evaluated TH declarations into *.th.hs files
-dunique-increment=⟨i⟩
Set the increment for the generated Unique's to ⟨i⟩.
-dverbose-core2core
Show output from each core-to-core pass
-dverbose-stg2stg
Show output from each STG-to-STG pass
-falignment-sanitisation
Compile with alignment checks for all info table dereferences.
-fcatch-nonexhaustive-cases
Add a default error alternative to case expressions without a default alternative.
-fcheck-prim-bounds
Instrument array primops with bounds checks.
-fcmm-thread-sanitizer
Enable ThreadSanitizer instrumentation of memory accesses.
-fdistinct-constructor-tables
Generate a fresh info table for each usage of a data constructor.
-fdump-with-ways
Include the tag of the enabled ways in the extension of dump files.
-finfo-table-map
Embed a lookup table in the generated binary which maps the address of an info
table to the source position the closure originated from.
-finfo-table-map-with-fallback
Include info tables with no source location information in the info table map.
-finfo-table-map-with-stack
Include info tables for STACK closures in the info table map.
-fllvm-fill-undef-with-garbage
Intruct LLVM to fill dead STG registers with garbage
-fno-info-table-map-with-fallback
Omit info tables with no source location information from the info table map.
-fno-info-table-map-with-stack
Omit info tables for STACK closures from the info table map.
-fproc-alignment
Align functions at given boundary.
-g Produce DWARF debug information in compiled object files. ⟨n⟩ can be 0, 1, or 2,
with higher numbers producing richer output. If ⟨n⟩ is omitted, level 2 is assumed.
C pre-processor
-cpp Run the C pre-processor on Haskell source files
-D⟨symbol⟩[=⟨value⟩]
Define a symbol in the C pre-processor
-I⟨dir⟩
Add ⟨dir⟩ to the directory search list for #include files
-U⟨symbol⟩
Undefine a symbol in the C pre-processor
Finding imports
-i Empty the import directory list
-i⟨dir⟩[:⟨dir⟩]*
add ⟨dir⟩, ⟨dir2⟩, etc. to import path
Interactive mode
-fbreak-on-error
Break on uncaught exceptions and errors
-fbreak-on-exception
Break on any exception thrown
-fghci-hist-size=⟨n⟩
Set the number of entries GHCi keeps for :history. See The GHCi Debugger.
-fghci-leak-check
(Debugging only) check for space leaks when loading new modules in GHCi.
-fimplicit-import-qualified
Put in scope qualified identifiers for every loaded module
-flocal-ghci-history
Use current directory for the GHCi command history file .ghci-history.
-fno-it
No longer set the special variable it.
-fprint-bind-result
Turn on printing of binding results in GHCi
-fprint-evld-with-show
Instruct :print to use Show instances where possible.
-fshow-loaded-modules
Show the names of modules that GHCi loaded after a :load command.
-ghci-script
Read additional .ghci files
-ignore-dot-ghci
Disable reading of .ghci files
-interactive-print ⟨name⟩
Select the function to use for printing evaluated expressions in GHCi
Interface files
--show-iface ⟨file⟩
See Modes of operation.
-ddump-hi
Dump the new interface to stdout
-ddump-hi-diffs
Show the differences vs. the old interface
-ddump-minimal-imports
Dump a minimal set of imports
Keeping intermediate files
-keep-hc-file
Retain intermediate .hc files.
-keep-hi-files
Retain intermediate .hi files (the default).
-keep-hscpp-file
Retain intermediate .hscpp files.
-keep-llvm-file
Retain intermediate LLVM .ll files. Implies -fllvm.
-keep-o-files
Retain intermediate .o files (the default).
-keep-s-file
Retain intermediate .s files.
-keep-tmp-files
Retain all intermediate temporary files.
Language options
-XAllowAmbiguousTypes
Allow the user to write ambiguous types, and the type inference engine to infer
them.
-XApplicativeDo
Enable Applicative do-notation desugaring
-XArrows
Enable arrow notation extension
-XBangPatterns
Enable bang patterns.
-XBinaryLiterals
Enable support for binary literals.
-XBlockArguments
Allow do blocks and other constructs as function arguments.
-XCApiFFI
Enable the CAPI calling convention.
-XConstrainedClassMethods
Enable constrained class methods.
-XConstraintKinds
Enable a kind of constraints.
-XCPP Enable the C preprocessor.
-XCUSKs
Enable detection of complete user-supplied kind signatures.
-XDataKinds
Enable datatype promotion.
-XDatatypeContexts
Allow contexts on data types.
-XDeepSubsumption
Enable deep subsumption
-XDefaultSignatures
Enable default signatures.
-XDeriveAnyClass
Enable deriving for any class.
-XDeriveDataTypeable
Enable deriving for the Data class.
-XDeriveFoldable
Enable deriving for the Foldable class. Implied by DeriveTraversable.
-XDeriveFunctor
Enable deriving for the Functor class. Implied by DeriveTraversable.
-XDeriveGeneric
Enable deriving for the Generic class.
-XDeriveLift
Enable deriving for the Lift class
-XDeriveTraversable
Enable deriving for the Traversable class. Implies DeriveFunctor and
DeriveFoldable.
-XDerivingStrategies
Enables deriving strategies.
-XDerivingVia
Enable deriving instances via types of the same runtime representation. Implies
DerivingStrategies.
-XDisambiguateRecordFields
Enable record field disambiguation. Implied by RecordWildCards.
-XDuplicateRecordFields
Allow definition of record types with identically-named fields.
-XEmptyCase
Allow empty case alternatives.
-XEmptyDataDecls
Allow definition of empty data types.
-XEmptyDataDeriving
Allow deriving instances of standard type classes for empty data types.
-XExistentialQuantification
Enable liberalised type synonyms.
-XExplicitForAll
Enable explicit universal quantification. Implied by ScopedTypeVariables,
LiberalTypeSynonyms, RankNTypes and ExistentialQuantification.
-XExplicitNamespaces
Enable using the keyword type to specify the namespace of entries in imports and
exports (Explicit namespaces in import/export). Implied by TypeOperators and
TypeFamilies.
-XExtendedDefaultRules
Use GHCi's extended default rules in a normal module.
-XFieldSelectors
Control visibility of field selector functions.
-XFlexibleContexts
Remove some restrictions on class contexts
-XFlexibleInstances
Enable flexible instances. Implies TypeSynonymInstances.
-XForeignFunctionInterface
Enable foreign function interface.
-XFunctionalDependencies
Enable functional dependencies. Implies MultiParamTypeClasses.
-XGADTs
Enable generalised algebraic data types. Implies GADTSyntax and MonoLocalBinds.
-XGADTSyntax
Enable generalised algebraic data type syntax.
-XGeneralisedNewtypeDeriving
Enable newtype deriving.
-XGeneralizedNewtypeDeriving
Enable newtype deriving.
-XGHC2021
Use GHC’s set of default language extensions from 2021
-XGHCForeignImportPrim
Enable prim calling convention. Intended for internal use only.
-XHaskell2010
Use the Haskell 2010 language variant.
-XHaskell98
Use the Haskell 98 language variant.
-XHexFloatLiterals
Enable support for hexadecimal floating point literals.
-XImplicitParams
Enable Implicit Parameters.
-XImportQualifiedPost
ImportQualifiedPost allows the syntax import M qualified
-XImpredicativeTypes
Enable impredicative types. Implies RankNTypes.
-XIncoherentInstances
Enable incoherent instances. Implies OverlappingInstances.
-XInstanceSigs
Enable instance signatures.
-XInterruptibleFFI
Enable interruptible FFI.
-XKindSignatures
Enable kind signatures. Implied by TypeFamilies and PolyKinds.
-XLambdaCase
Enable lambda-case expressions.
-XLexicalNegation
Use whitespace to determine whether the minus sign stands for negation or
subtraction.
-XLiberalTypeSynonyms
Enable liberalised type synonyms.
-XLinearTypes
Enable linear types.
-XMagicHash
Allow # as a postfix modifier on identifiers.
-XMonadComprehensions
Enable monad comprehensions.
-XMonoLocalBinds
Enable do not generalise local bindings. Implied by TypeFamilies and GADTs.
-XMultiParamTypeClasses
Enable multi parameter type classes. Implied by FunctionalDependencies.
-XMultiWayIf
Enable multi-way if-expressions.
-XNamedFieldPuns
Enable record puns.
-XNamedWildCards
Enable named wildcards.
-XNegativeLiterals
Enable support for negative literals.
-XNoImplicitPrelude
Don't implicitly import Prelude. Implied by RebindableSyntax.
-XNoMonomorphismRestriction
Disable the monomorphism restriction.
-XNondecreasingIndentation
Allow nested contexts to be at the same indentation level as its enclosing context.
-XNoPatternGuards
Disable pattern guards. Implied by Haskell98.
-XNoTraditionalRecordSyntax
Disable support for traditional record syntax (as supported by Haskell 98) C {f =
x}
-XNPlusKPatterns
Enable support for n+k patterns. Implied by Haskell98.
-XNullaryTypeClasses
Deprecated, does nothing. nullary (no parameter) type classes are now enabled using
MultiParamTypeClasses.
-XNumDecimals
Enable support for 'fractional' integer literals.
-XNumericUnderscores
Enable support for numeric underscores.
-XOverlappingInstances
Enable overlapping instances.
-XOverloadedLabels
Enable overloaded labels.
-XOverloadedLists
Enable overloaded lists.
-XOverloadedRecordDot
Record '.' syntax
-XOverloadedRecordUpdate
Record '.' syntax record updates
-XOverloadedStrings
Enable overloaded string literals.
-XPackageImports
Enable package-qualified imports.
-XParallelListComp
Enable parallel list comprehensions.
-XPartialTypeSignatures
Enable partial type signatures.
-XPatternSynonyms
Enable pattern synonyms.
-XPolyKinds
Enable kind polymorphism. Implies KindSignatures.
-XPostfixOperators
Enable postfix operators.
-XQualifiedDo
Enable qualified do-notation desugaring.
-XQuantifiedConstraints
Allow forall quantifiers in constraints.
-XQuasiQuotes
Enable quasiquotation.
-XRank2Types
Enable rank-2 types. Synonym for RankNTypes.
-XRankNTypes
Enable rank-N types. Implied by ImpredicativeTypes.
-XRebindableSyntax
Employ rebindable syntax. Implies NoImplicitPrelude.
-XRecordWildCards
Enable record wildcards. Implies DisambiguateRecordFields.
-XRecursiveDo
Enable recursive do (mdo) notation.
-XRoleAnnotations
Enable role annotations.
-XSafe Enable the Safe Haskell Safe mode.
-XScopedTypeVariables
Enable lexically-scoped type variables.
-XStandaloneDeriving
Enable standalone deriving.
-XStandaloneKindSignatures
Allow the use of standalone kind signatures.
-XStarIsType
Treat * as Data.Kind.Type.
-XStaticPointers
Enable static pointers.
-XStrict
Make bindings in the current module strict by default.
-XStrictData
Enable default strict datatype fields.
-XTemplateHaskell
Enable Template Haskell.
-XTemplateHaskellQuotes
Enable quotation subset of Template Haskell.
-XTransformListComp
Enable generalised list comprehensions.
-XTrustworthy
Enable the Safe Haskell Trustworthy mode.
-XTupleSections
Enable tuple sections.
-XTypeApplications
Enable type application syntax in terms, patterns and types.
-XTypeData
Enable type data declarations.
-XTypeFamilies
Enable type families. Implies ExplicitNamespaces, KindSignatures, and
MonoLocalBinds.
-XTypeFamilyDependencies
Enable injective type families. Implies TypeFamilies.
-XTypeInType
Deprecated. Enable kind polymorphism and datatype promotion.
-XTypeOperators
Enable type operators. Implies ExplicitNamespaces.
-XTypeSynonymInstances
Enable type synonyms in instance heads. Implied by FlexibleInstances.
-XUnboxedSums
Enable unboxed sums.
-XUnboxedTuples
Enable the use of unboxed tuple syntax.
-XUndecidableInstances
Enable undecidable instances.
-XUndecidableSuperClasses
Allow all superclass constraints, including those that may result in
non-termination of the typechecker.
-XUnicodeSyntax
Enable unicode syntax.
-XUnliftedDatatypes
Enable unlifted data types.
-XUnliftedFFITypes
Enable unlifted FFI types
-XUnliftedNewtypes
Enable unlifted newtypes.
-XUnsafe
Enable Safe Haskell Unsafe mode.
-XViewPatterns
Enable view patterns.
Linking options
-c Stop after generating object (.o) file
-debug Use the debugging runtime
-dylib-install-name ⟨path⟩
Set the install name (via -install_name passed to Apple's linker), specifying the
full install path of the library file. Any libraries or executables that link with
it later will pick up that path as their runtime search location for it.
(Darwin/OS X only)
-dynamic
Build dynamically-linked object files and executables
-dynload
Selects one of a number of modes for finding shared libraries at runtime.
-eventlog
Enable runtime event tracing
-fcompact-unwind
Instruct the linker to produce a __compact_unwind section.
-fkeep-cafs
Do not garbage-collect CAFs (top-level expressions) at runtime
-flink-rts
Link the runtime when generating a shared or static library
-fno-embed-manifest
Do not embed the manifest in the executable (Windows only)
-fno-gen-manifest
Do not generate a manifest file (Windows only)
-fno-shared-implib
Don't generate an import library for a DLL (Windows only)
-framework ⟨name⟩
On Darwin/OS X/iOS only, link in the framework ⟨name⟩. This option corresponds to
the -framework option for Apple's Linker.
-framework-path ⟨dir⟩
On Darwin/OS X/iOS only, add ⟨dir⟩ to the list of directories searched for
frameworks. This option corresponds to the -F option for Apple's Linker.
-fsplit-sections
Split sections for link-time dead-code stripping
-fuse-rpaths
Set the rpath based on -L flags
-fwhole-archive-hs-libs
When linking a binary executable, this inserts the flag -Wl,--whole-archive before
any -l flags for Haskell libraries, and -Wl,--no-whole-archive afterwards
-L ⟨dir⟩
Add ⟨dir⟩ to the list of directories searched for libraries
-l ⟨lib⟩
Link in library ⟨lib⟩
-main-is ⟨thing⟩
Set main module and function
-no-hs-main
Don't assume this program contains main
-no-pie
Don't instruct the linker to produce a position-independent executable.
-no-rtsopts-suggestions
Don't print RTS suggestions about linking with
-rtsopts[=⟨none|some|all|ignore|ignoreAll⟩].
-package ⟨name⟩
Expose package ⟨pkg⟩
-pie Instruct the linker to produce a position-independent executable.
-rdynamic
This instructs the linker to add all symbols, not only used ones, to the dynamic
symbol table. Currently Linux and Windows/MinGW32 only. This is equivalent to using
-optl -rdynamic on Linux, and -optl -export-all-symbols on Windows.
-rtsopts[=⟨none|some|all|ignore|ignoreAll⟩]
Control whether the RTS behaviour can be tweaked via command-line flags and the
GHCRTS environment variable. Using none means no RTS flags can be given; some means
only a minimum of safe options can be given (the default); all (or no argument at
all) means that all RTS flags are permitted; ignore means RTS flags can be given,
but are treated as regular arguments and passed to the Haskell program as
arguments; ignoreAll is the same as ignore, but GHCRTS is also ignored. -rtsopts
does not affect -with-rtsopts behavior; flags passed via -with-rtsopts are used
regardless of -rtsopts.
-shared
Generate a shared library (as opposed to an executable)
-static
Use static Haskell libraries
-staticlib
Generate a standalone static library (as opposed to an executable). This is useful
when cross compiling. The library together with all its dependencies ends up in in
a single static library that can be linked against.
-threaded
Use the threaded runtime
-with-rtsopts=⟨opts⟩
Set the default RTS options to ⟨opts⟩.
Miscellaneous options
-ddump-mod-cycles
Dump module cycles
-fexternal-interpreter
Run interpreted code in a separate process
-ffamily-application-cache
Use a cache when reducing type family applications
-fglasgow-exts
Deprecated. Enable most language extensions; see Controlling extensions for exactly
which ones.
-fno-safe-haskell
Disable Safe Haskell
-ghcversion-file ⟨path to ghcversion.h⟩
(GHC as a C compiler only) Use this ghcversion.h file
-H ⟨size⟩
Set the minimum size of the heap to ⟨size⟩
-hidden-module ⟨module name⟩
A module which should not be visible outside its unit.
-j[⟨n⟩]
When compiling with --make, compile ⟨n⟩ modules in parallel.
-reexported-module ⟨module name⟩
A module which should be reexported from this unit.
-this-package-name ⟨unit-id⟩
The name of the package which this module would be part of when installed.
-unit @⟨filename⟩
Specify the options to build a specific unit.
-working-dir ⟨dir⟩
Specify the directory a unit is expected to be compiled in.
Modes of operation
--frontend ⟨module⟩
run GHC with the given frontend plugin; see Frontend plugins for details.
--help Display help
--info display information about the compiler
--interactive
Interactive mode - normally used by just running ghci; see Using GHCi for details.
--make Build a multi-module Haskell program, automatically figuring out dependencies.
Likely to be much easier, and faster, than using make; see Using ghc --make for
details.
--numeric-version
display GHC version (numeric only)
--print-booter-version
display bootstrap compiler version
--print-build-platform
display platform on which GHC was built
--print-c-compiler-flags
C compiler flags used to build GHC
--print-c-compiler-link-flags
C linker flags used to build GHC
--print-debug-on
print whether GHC was built with -DDEBUG
--print-global-package-db
display GHC's global package database directory
--print-have-interpreter
display whether GHC was built with interactive support
--print-have-native-code-generator
display whether target platform has NCG support
--print-host-platform
display host platform of GHC
--print-ld-flags
display linker flags used to compile GHC
--print-leading-underscore
display use of leading underscores on symbol names
--print-libdir
display GHC library directory
--print-object-splitting-supported
display whether GHC supports object splitting
--print-project-git-commit-id
display Git commit id GHC is built from
--print-project-version
display GHC version
--print-rts-ways
display which way RTS was built
--print-stage
display stage number of GHC
--print-support-smp
display whether GHC was compiled with SMP support
--print-tables-next-to-code
display whether GHC was compiled with --enable-tables-next-to-code
--print-target-platform
display target platform of GHC
--print-unregisterised
display whether this GHC was built in unregisterised mode
--run ⟨file⟩
Run a Haskell program.
--show-iface ⟨file⟩
display the contents of an interface file.
--show-options
display the supported command line options
--supported-extensions
display the supported language extensions
--version
display GHC version
-e ⟨expr⟩
Evaluate expr; see Expression evaluation mode for details.
-M generate dependency information suitable for use in a Makefile; see Dependency
generation for details.
-shared
Create a shared object.
Individual optimizations
-fasm-shortcutting
Enable shortcutting on assembly.
-fbinary-blob-threshold=⟨n⟩
default: 500K. Tweak assembly generator for binary blobs.
-fblock-layout-cfg
Use the new cfg based block layout algorithm.
-fblock-layout-weightless
Ignore cfg weights for code layout.
-fblock-layout-weights
Sets edge weights used by the new code layout algorithm.
-fcall-arity
Enable call-arity optimisation. Implied by -O.
-fcase-folding
Enable constant folding in case expressions. Implied by -O.
-fcase-merge
Enable case-merging. Implied by -O.
-fcmm-control-flow
Enable control flow optimisation in the Cmm backend. Implied by -O.
-fcmm-elim-common-blocks
Enable Cmm common block elimination. Implied by -O.
-fcmm-sink
Enable Cmm sinking. Implied by -O.
-fcmm-static-pred
Enable static control flow prediction. Implied by -O.
-fcore-constant-folding
Enable constant folding in Core. Implied by -O.
-fcpr-anal
Turn on Constructed Product Result analysis. Implied by -O.
-fcross-module-specialise
Turn on specialisation of overloaded functions imported from other modules.
-fcse Enable common sub-expression elimination. Implied by -O.
-fdicts-cheap
Make dictionary-valued expressions seem cheap to the optimiser.
-fdicts-strict
Make dictionaries strict. Implied by -O2.
-fdmd-tx-dict-sel
(deprecated) Use a special demand transformer for dictionary selectors.
-fdmd-unbox-width=⟨n⟩
default: 3. Boxity analysis pretends that returned records with this many fields
can be unboxed.
-fdo-eta-reduction
Enable eta-reduction. Implied by -O.
-fdo-lambda-eta-expansion
Enable lambda eta-expansion. Always enabled by default.
-feager-blackholing
Turn on eager blackholing
-fenable-rewrite-rules
Switch on all rewrite rules (including rules generated by automatic specialisation
of overloaded functions). Implied by -O.
-fexcess-precision
Enable excess intermediate precision
-fexitification
Enables exitification optimisation. Implied by -O.
-fexpose-all-unfoldings
Expose all unfoldings, even for very large or recursive functions.
-ffloat-in
Turn on the float-in transformation. Implied by -O.
-ffull-laziness
Turn on full laziness (floating bindings outwards). Implied by -O.
-ffun-to-thunk
(deprecated) superseded by -ffull-laziness.
-fignore-asserts
Ignore assertions in the source. Implied by -O.
-fignore-interface-pragmas
Ignore pragmas in interface files. Implied by -O0 only.
-finline-generics
Annotate methods of derived Generic and Generic1 instances with INLINE[1] pragmas
based on heuristics. Implied by -O.
-finline-generics-aggressively
Annotate methods of all derived Generic and Generic1 instances with INLINE[1]
pragmas.
-flate-dmd-anal
Run demand analysis again, at the end of the simplification pipeline
-flate-specialise
Run a late specialisation pass
-fliberate-case
Turn on the liberate-case transformation. Implied by -O2.
-fliberate-case-threshold=⟨n⟩
default: 2000. Set the size threshold for the liberate-case transformation to ⟨n⟩
-fllvm-pass-vectors-in-regs
(deprecated) Does nothing
-flocal-float-out
Enable local floating definitions out of let-binds.
-flocal-float-out-top-level
Enable local floating to float top-level bindings
-floopification
Turn saturated self-recursive tail-calls into local jumps in the generated
assembly. Implied by -O.
-fmax-inline-alloc-size=⟨n⟩
default: 128. Set the maximum size of inline array allocations to ⟨n⟩ bytes
(default: 128).
-fmax-inline-memcpy-insns=⟨n⟩
default: 32. Inline memcpy calls if they would generate no more than ⟨n⟩ pseudo
instructions.
-fmax-inline-memset-insns=⟨n⟩
default: 32. Inline memset calls if they would generate no more than ⟨n⟩ pseudo
instructions
-fmax-simplifier-iterations=⟨n⟩
default: 4. Set the max iterations for the simplifier.
-fmax-uncovered-patterns=⟨n⟩
default: 4. Set the maximum number of patterns to display in warnings about
non-exhaustive ones.
-fmax-worker-args=⟨n⟩
default: 10. Maximum number of value arguments for a worker.
-fno-opt-coercion
Turn off the coercion optimiser
-fno-pre-inlining
Turn off pre-inlining
-fno-state-hack
Turn off the state hackwhereby any lambda with a real-world state token as argument
is considered to be single-entry. Hence OK to inline things inside it.
-fomit-interface-pragmas
Don't generate interface pragmas. Implied by -O0 only.
-fomit-yields
Omit heap checks when no allocation is being performed.
-foptimal-applicative-do
Use a slower but better algorithm for ApplicativeDo
-fpedantic-bottoms
Make GHC be more precise about its treatment of bottom (but see also
-fno-state-hack). In particular, GHC will not eta-expand through a case expression.
-fpolymorphic-specialisation
Allow specialisation to abstract over free type variables
-fregs-graph
Use the graph colouring register allocator for register allocation in the native
code generator.
-fregs-iterative
Use the iterative coalescing graph colouring register allocator in the native code
generator.
-fsimpl-tick-factor=⟨n⟩
default: 100. Set the percentage factor for simplifier ticks.
-fsimplifier-phases=⟨n⟩
default: 2. Set the number of phases for the simplifier. Ignored with -O0.
-fsolve-constant-dicts
When solving constraints, try to eagerly solve super classes using available
dictionaries.
-fspec-constr
Turn on the SpecConstr transformation. Implied by -O2.
-fspec-constr-count=⟨n⟩
default: 3.* Set to ⟨n⟩ the maximum number of specialisations that will be created
for any one function by the SpecConstr transformation.
-fspec-constr-keen
Specialize a call with an explicit constructor argument, even if the argument is
not scrutinised in the body of the function
-fspec-constr-threshold=⟨n⟩
default: 2000. Set the size threshold for the SpecConstr transformation to ⟨n⟩.
-fspecialise
Turn on specialisation of overloaded functions. Implied by -O.
-fspecialise-aggressively
Turn on specialisation of overloaded functions regardless of size, if unfolding is
available
-fstatic-argument-transformation
Turn on the static argument transformation.
-fstg-cse
Enable common sub-expression elimination on the STG intermediate language
-fstg-lift-lams
Enable late lambda lifting on the STG intermediate language. Implied by -O2.
-fstg-lift-lams-known
Allow turning known into unknown calls while performing late lambda lifting.
-fstg-lift-lams-non-rec-args
Create top-level non-recursive functions with at most <n> parameters while
performing late lambda lifting.
-fstg-lift-lams-rec-args
Create top-level recursive functions with at most <n> parameters while performing
late lambda lifting.
-fstrictness
Turn on demand analysis. Implied by -O. Implies -fworker-wrapper
-fstrictness-before=⟨n⟩
Run an additional demand analysis before simplifier phase ⟨n⟩
-funbox-small-strict-fields
Flatten strict constructor fields with a pointer-sized representation. Implied by
-O.
-funbox-strict-fields
Flatten strict constructor fields
-funfolding-case-scaling=⟨n⟩
default: 30. Apply a penalty of (inlining_cost * 1/n) for each level of case
nesting.
-funfolding-case-threshold=⟨n⟩
default: 2. Reduce inlining for cases nested deeper than n.
-funfolding-creation-threshold=⟨n⟩
default: 750. Tweak unfolding settings.
-funfolding-dict-discount=⟨n⟩
default: 30. Tweak unfolding settings.
-funfolding-fun-discount=⟨n⟩
default: 60. Tweak unfolding settings.
-funfolding-keeness-factor=⟨n⟩
This has been deprecated in GHC 9.0.1.
-funfolding-use-threshold=⟨n⟩
default: 80. Tweak unfolding settings.
-fworker-wrapper
Enable the worker/wrapper transformation.
-fworker-wrapper-cbv
Enable w/w splits for wrappers whos sole purpose is evaluating arguments.
Optimization levels
-O Enable level 1 optimisations
-O0 Disable optimisations (default)
-O2 Enable level 2 optimisations
-O⟨n⟩ Any -On where n > 2 is the same as -O2.
Package options
-clear-package-db
Clear the package db stack.
-distrust ⟨pkg⟩
Expose package ⟨pkg⟩ and set it to be distrusted. See Safe Haskell.
-distrust-all-packages
Distrust all packages by default. See Safe Haskell.
-fpackage-trust
Enable Safe Haskell trusted package requirement for trustworthy modules.
-global-package-db
Add the global package db to the stack.
-hide-all-packages
Hide all packages by default
-hide-package ⟨pkg⟩
Hide package ⟨pkg⟩
-ignore-package ⟨pkg⟩
Ignore package ⟨pkg⟩
-no-auto-link-packages
Don't automatically link in the base and rts packages.
-no-global-package-db
Remove the global package db from the stack.
-no-user-package-db
Remove the user's package db from the stack.
-package ⟨pkg⟩
Expose package ⟨pkg⟩
-package-db ⟨file⟩
Add ⟨file⟩ to the package db stack.
-package-env ⟨file⟩|⟨name⟩
Use the specified package environment.
-package-id ⟨unit-id⟩
Expose package by id ⟨unit-id⟩
-this-unit-id ⟨unit-id⟩
Compile to be part of unit (i.e. package) ⟨unit-id⟩
-trust ⟨pkg⟩
Expose package ⟨pkg⟩ and set it to be trusted. See Safe Haskell.
-user-package-db
Add the user's package db to the stack.
Phases of compilation
--merge-objs
Merge a set of objects into a GHCi library.
-C Stop after generating C (.hc file)
-c Stop after generating object (.o) file
-E Stop after preprocessing (.hspp file)
-F Enable the use of a pre-processor (set with -pgmF ⟨cmd⟩)
-S Stop after generating assembly (.s file)
-x ⟨suffix⟩
Override default behaviour for source files
Overriding external programs
-pgma ⟨cmd⟩
Use ⟨cmd⟩ as the assembler
-pgmc ⟨cmd⟩
Use ⟨cmd⟩ as the C compiler
-pgmcxx ⟨cmd⟩
Use ⟨cmd⟩ as the C++ compiler
-pgmdll ⟨cmd⟩
Use ⟨cmd⟩ as the DLL generator
-pgmF ⟨cmd⟩
Use ⟨cmd⟩ as the pre-processor (with -F only)
-pgmi ⟨cmd⟩
Use ⟨cmd⟩ as the external interpreter command.
-pgminstall_name_tool ⟨cmd⟩
Use ⟨cmd⟩ as the program to inject runpath into mach-o dylibs on macOS
-pgmL ⟨cmd⟩
Use ⟨cmd⟩ as the literate pre-processor
-pgml ⟨cmd⟩
Use ⟨cmd⟩ as the linker
-pgmlc ⟨cmd⟩
Use ⟨cmd⟩ as the LLVM compiler
-pgmlm ⟨cmd⟩
Use ⟨cmd⟩ as the linker when merging object files
-pgmlo ⟨cmd⟩
Use ⟨cmd⟩ as the LLVM optimiser
-pgmotool ⟨cmd⟩
Use ⟨cmd⟩ as the program to inspect mach-o dylibs on macOS
-pgmP ⟨cmd⟩
Use ⟨cmd⟩ as the C pre-processor (with -cpp only)
-pgms ⟨cmd⟩
Use ⟨cmd⟩ as the splitter
-pgmwindres ⟨cmd⟩
Use ⟨cmd⟩ as the program for embedding manifests on Windows.
Phase-specific options
-opta ⟨option⟩
pass ⟨option⟩ to the assembler
-optc ⟨option⟩
pass ⟨option⟩ to the C compiler
-optcxx ⟨option⟩
pass ⟨option⟩ to the C++ compiler
-optdll ⟨option⟩
pass ⟨option⟩ to the DLL generator
-optF ⟨option⟩
pass ⟨option⟩ to the custom pre-processor
-opti ⟨option⟩
pass ⟨option⟩ to the interpreter sub-process.
-optL ⟨option⟩
pass ⟨option⟩ to the literate pre-processor
-optl ⟨option⟩
pass ⟨option⟩ to the linker
-optlc ⟨option⟩
pass ⟨option⟩ to the LLVM compiler
-optlm ⟨option⟩
pass ⟨option⟩ to the linker when merging object files.
-optlo ⟨option⟩
pass ⟨option⟩ to the LLVM optimiser
-optP ⟨option⟩
pass ⟨option⟩ to cpp (with -cpp only)
-optwindres ⟨option⟩
pass ⟨option⟩ to windres.
-pgmc-supports-no-pie
(deprecated) Indicate that the linker supports -no-pie
-pgml-supports-no-pie
Indicate that the linker supports -no-pie
Platform-specific options
-mavx (x86 only) Enable support for AVX SIMD extensions
-mavx2 (x86 only) Enable support for AVX2 SIMD extensions
-mavx512cd
(x86 only) Enable support for AVX512-CD SIMD extensions
-mavx512er
(x86 only) Enable support for AVX512-ER SIMD extensions
-mavx512f
(x86 only) Enable support for AVX512-F SIMD extensions
-mavx512pf
(x86 only) Enable support for AVX512-PF SIMD extensions
-mbmi (x86 only) Use BMI1 for bit manipulation operations
-mbmi2 (x86 only) Use BMI2 for bit manipulation operations
-msse (x86 only) Use SSE for floating-point operations
-msse2 (x86 only) Use SSE2 for floating-point operations
-msse3 (x86 only) Use SSE3 for floating-point operations
-msse4 (x86 only) Use SSE4 for floating-point operations
-msse4.2
(x86 only) Use SSE4.2 for floating-point operations
Compiler plugins
-fclear-plugins
Clear the list of active plugins
-fplugin-library=⟨file-path⟩;⟨unit-id⟩;⟨module⟩;⟨args⟩
Load a pre-compiled static plugin from an external library
-fplugin-opt=⟨module⟩:⟨args⟩
Give arguments to a plugin module; module must be specified with -fplugin=⟨module⟩
-fplugin-trustworthy
Trust the used plugins and no longer mark the compiled module as unsafe
-fplugin=⟨module⟩
Load a plugin exported by a given module
-hide-all-plugin-packages
Hide all packages for plugins by default
-plugin-package ⟨pkg⟩
Expose ⟨pkg⟩ for plugins
-plugin-package-id ⟨pkg-id⟩
Expose ⟨pkg-id⟩ for plugins
Profiling
-auto (deprecated) Alias for -fprof-auto-exported
-auto-all
(deprecated) Alias for -fprof-auto
-caf-all
(deprecated) Alias for -fprof-cafs
-fno-prof-count-entries
Do not collect entry counts
-fprof-auto
Auto-add SCC\ s to all bindings not marked INLINE
-fprof-auto-calls
Auto-add SCC\ s to all call sites
-fprof-auto-exported
Auto-add SCC\ s to all exported bindings not marked INLINE
-fprof-auto-top
Auto-add SCC\ s to all top-level bindings not marked INLINE
-fprof-cafs
Auto-add SCC\ s to all CAFs
-fprof-callers=⟨name⟩
Auto-add SCC\ s to all call-sites of the named function.
-fprof-late
Auto-add SCC\ s to all top level bindings after the core pipeline has run.
-fprof-late-inline
Auto-add SCC\ s to all top level bindings after the optimizer has run and retain
them when inlining.
-fprof-manual
Process manual SCC annotations.
-no-auto
(deprecated) Alias for -fno-prof-auto
-no-auto-all
(deprecated) Alias for -fno-prof-auto
-no-caf-all
(deprecated) Alias for -fno-prof-cafs
-prof Turn on profiling
-ticky Turn on ticky-ticky profiling
-ticky-allocd
Track the number of times each closure type is allocated.
-ticky-ap-thunk
Don't use standard AP thunks on order to get more reliable entry counters.
-ticky-dyn-thunk
Track allocations of dynamic thunks
-ticky-LNE
Treat join point binders similar to thunks/functions.
-ticky-tag-checks
Emit dummy ticky counters to record how many tag-inference checks tag inference
avoided.
Program coverage
-fhpc Turn on Haskell program coverage instrumentation
-hpcdir⟨dir⟩
Set the directory where GHC places .mix files.
Recompilation checking
-exclude-module=⟨file⟩
Regard ⟨file⟩ as "stable"; i.e., exclude it from having dependencies on it.
-fforce-recomp
Turn off recompilation checking. This is implied by any -ddump-X option when
compiling a single file (i.e. when using -c).
-fignore-hpc-changes
Do not recompile modules just to match changes to HPC flags. This is especially
useful for avoiding recompilation when using GHCi, and is enabled by default for
GHCi.
-fignore-optim-changes
Do not recompile modules just to match changes to optimisation flags. This is
especially useful for avoiding recompilation when using GHCi, and is enabled by
default for GHCi.
-include-cpp-deps
Include preprocessor dependencies
-include-pkg-deps
Regard modules imported from packages as unstable
Redirecting output
-dep-makefile ⟨file⟩
Use ⟨file⟩ as the makefile
-dep-suffix ⟨suffix⟩
Make dependencies that declare that files with suffix .⟨suf⟩⟨osuf⟩ depend on
interface files with suffix .⟨suf⟩hi
-dumpdir ⟨dir⟩
redirect dump files
-dynhisuf ⟨suffix⟩
set the suffix to use for dynamic interface files
-dyno ⟨file⟩
set dynamic output filename
-dynohi ⟨file⟩
set the filename in which to put the dynamic interface
-dynosuf ⟨suffix⟩
set the dynamic output file suffix
-hcsuf ⟨suffix⟩
set the suffix to use for intermediate C files
-hidir ⟨dir⟩
set directory for interface files
-hiedir ⟨dir⟩
set directory for extended interface files
-hiesuf ⟨suffix⟩
set the suffix to use for extended interface files
-hisuf ⟨suffix⟩
set the suffix to use for interface files
-o ⟨file⟩
set output filename
-odir ⟨dir⟩
set directory for object files
-ohi ⟨file⟩
set the filename in which to put the interface
-osuf ⟨suffix⟩
set the output file suffix
-outputdir ⟨dir⟩
set output directory
-stubdir ⟨dir⟩
redirect FFI stub files
Temporary files
-tmpdir ⟨dir⟩
set the directory for temporary files
Verbosity options
-fabstract-refinement-hole-fits
default: off. Toggles whether refinements where one or more of the holes are
abstract are reported.
-fdefer-diagnostics
Defer and group diagnostic messages by severity
-fdiagnostics-color=⟨always|auto|never⟩
Use colors in error messages
-fdiagnostics-show-caret
Whether to show snippets of original source code
-ferror-spans
Output full span in error messages
-fhide-source-paths
hide module source and object paths
-fkeep-going
Continue compilation as far as possible on errors
-fmax-refinement-hole-fits=⟨n⟩
default: 6. Set the maximum number of refinement hole fits for typed holes to
display in type error messages.
-fmax-relevant-binds=⟨n⟩
default: 6. Set the maximum number of bindings to display in type error messages.
-fmax-valid-hole-fits=⟨n⟩
default: 6. Set the maximum number of valid hole fits for typed holes to display in
type error messages.
-fno-show-valid-hole-fits
Disables showing a list of valid hole fits for typed holes in type error messages.
-fno-sort-valid-hole-fits
Disables the sorting of the list of valid hole fits for typed holes in type error
messages.
-fprint-axiom-incomps
Display equation incompatibilities in closed type families
-fprint-equality-relations
Distinguish between equality relations when printing
-fprint-expanded-synonyms
In type errors, also print type-synonym-expanded types.
-fprint-explicit-coercions
Print coercions in types
-fprint-explicit-foralls
Print explicit forall quantification in types. See also ExplicitForAll
-fprint-explicit-kinds
Print explicit kind foralls and kind arguments in types. See also KindSignatures
-fprint-explicit-runtime-reps
Print RuntimeRep and Levity variables in types which are runtime-representation
polymorphic.
-fprint-potential-instances
display all available instances in type error messages
-fprint-redundant-promotion-ticks
Print redundant DataKinds promotion ticks
-fprint-typechecker-elaboration
Print extra information from typechecker.
-fprint-unicode-syntax
Use unicode syntax when printing expressions, types and kinds. See also
UnicodeSyntax
-frefinement-level-hole-fits=⟨n⟩
default: off. Sets the level of refinement of the refinement hole fits, where level
n means that hole fits of up to n holes will be considered.
-freverse-errors
Output errors in reverse order
-fshow-docs-of-hole-fits
Toggles whether to show the documentation of the valid hole fits in the output.
-fshow-error-context
Whether to show textual information about error context
-fshow-hole-constraints
Show constraints when reporting typed holes.
-fshow-hole-matches-of-hole-fits
Toggles whether to show the type of the additional holes in refinement hole fits.
-fshow-provenance-of-hole-fits
Toggles whether to show the provenance of the valid hole fits in the output.
-fshow-type-app-of-hole-fits
Toggles whether to show the type application of the valid hole fits in the output.
-fshow-type-app-vars-of-hole-fits
Toggles whether to show what type each quantified variable takes in a valid hole
fit.
-fshow-type-of-hole-fits
Toggles whether to show the type of the valid hole fits in the output.
-fsort-by-size-hole-fits
Sort valid hole fits by size.
-fsort-by-subsumption-hole-fits
Sort valid hole fits by subsumption.
-funclutter-valid-hole-fits
Unclutter the list of valid hole fits by not showing provenance nor type
applications of suggestions.
-Rghc-timing
Summarise timing stats for GHC (same as +RTS -tstderr).
-v verbose mode (equivalent to -v3)
-v⟨n⟩ set verbosity level
Warnings
-fdefer-out-of-scope-variables
Convert variable out of scope variables errors into warnings. Implied by
-fdefer-type-errors. See also -Wdeferred-out-of-scope-variables.
-fdefer-type-errors
Turn type errors into warnings, deferring the error until runtime. Implies
-fdefer-typed-holes and -fdefer-out-of-scope-variables. See also
-Wdeferred-type-errors
-fdefer-typed-holes
Convert typed hole errors into warnings, deferring the error until runtime.
Implied by -fdefer-type-errors. See also -Wtyped-holes.
-fenable-th-splice-warnings
Generate warnings for Template Haskell splices
-fhelpful-errors
Make suggestions for mis-spelled names.
-fmax-pmcheck-models=⟨n⟩
soft limit on the number of parallel models the pattern match checker should check
a pattern match clause against
-fshow-warning-groups
show which group an emitted warning belongs to.
-fvia-C
use the C code generator
-W enable normal warnings
-w disable all warnings
-Wall enable almost all warnings (details in Warnings and sanity-checking)
-Wall-missed-specialisations
warn when specialisation of any overloaded function fails.
-Wall-missed-specializations
alias for -Wall-missed-specialisations
-Wambiguous-fields
warn about ambiguous field selectors or updates
-Wauto-orphans
(deprecated) Does nothing
-Wcompat
enable future compatibility warnings (details in Warnings and sanity-checking)
-Wcompat-unqualified-imports
Report unqualified imports of core libraries which are expected to cause
compatibility problems in future releases.
-Wcpp-undef
warn on uses of the #if directive on undefined identifiers
-Wdefault
enable default flags
-Wdeferred-out-of-scope-variables
Report warnings when variable out-of-scope errors are deferred until runtime. See
-fdefer-out-of-scope-variables.
-Wdeferred-type-errors
Report warnings when deferred type errors are enabled. This option is enabled by
default. See -fdefer-type-errors.
-Wdeprecated-flags
warn about uses of commandline flags that are deprecated
-Wdeprecations
warn about uses of functions & types that have warnings or deprecated pragmas.
Alias for -Wwarnings-deprecations
-Wderiving-defaults
warn about default deriving when using both DeriveAnyClass and
GeneralizedNewtypeDeriving
-Wderiving-typeable
warn when Typeable is derived
-Wdodgy-exports
warn about dodgy exports
-Wdodgy-foreign-imports
warn about dodgy foreign imports
-Wdodgy-imports
warn about dodgy imports
-Wduplicate-constraints
warn when a constraint appears duplicated in a type signature
-Wduplicate-exports
warn when an entity is exported multiple times
-Wempty-enumerations
warn about enumerations that are empty
-Werror
make warnings fatal
-Weverything
enable all warnings supported by GHC
-Wextra
alias for -W
-Wforall-identifier
warn when forall is used as an identifier (at definition sites)
-Wgadt-mono-local-binds
warn when pattern matching on a GADT without MonoLocalBinds
-Whi-shadowing
(deprecated) warn when a .hi file in the current directory shadows a library
-Widentities
warn about uses of Prelude numeric conversions that are probably the identity (and
hence could be omitted)
-Wimplicit-kind-vars
(deprecated) warn when kind variables are implicitly quantified over.
-Wimplicit-lift
warn about implicit lift in Template Haskell quotes
-Wimplicit-prelude
warn when the Prelude is implicitly imported
-Winaccessible-code
warn about inaccessible code
-Wincomplete-patterns
warn when a pattern match could fail
-Wincomplete-record-updates
warn when a record update could fail
-Wincomplete-uni-patterns
warn when a pattern match in a lambda expression, pattern binding or a lazy pattern
could fail
-Winferred-safe-imports
warn when an explicitly Safe Haskell module imports a Safe-Inferred one
-Winline-rule-shadowing
Warn if a rewrite RULE might fail to fire because the function might be inlined
before the rule has a chance to fire. See How rules interact with INLINE/NOINLINE
pragmas.
-Winvalid-haddock
warn when a Haddock comment occurs in an invalid position
-Wloopy-superclass-solve
warn when creating potentially-loopy superclass constraint evidence
-Wmisplaced-pragmas
warn about uses of file header pragmas in the module body
-Wmissed-extra-shared-lib
Warn when GHCi can't load a shared lib.
-Wmissed-specialisations
warn when specialisation of an imported, overloaded function fails.
-Wmissed-specializations
alias for -Wmissed-specialisations
-Wmissing-deriving-strategies
warn when a deriving clause is missing a deriving strategy
-Wmissing-export-lists
warn when a module declaration does not explicitly list all exports
-Wmissing-exported-pattern-synonym-signatures
warn about pattern synonyms without signatures, only if they are exported
-Wmissing-exported-signatures
warn about top-level functions without signatures, only if they are exported
-Wmissing-exported-sigs
(deprecated) warn about top-level functions without signatures, only if they are
exported. takes precedence over -Wmissing-signatures
-Wmissing-fields
warn when fields of a record are uninitialised
-Wmissing-home-modules
warn when encountering a home module imported, but not listed on the command line.
Useful for cabal to ensure GHC won't pick up modules, not listed neither in
exposed-modules, nor in other-modules.
-Wmissing-import-lists
warn when an import declaration does not explicitly list all the names brought into
scope
-Wmissing-kind-signatures
warn when type declarations don't have kind signatures nor CUSKs
-Wmissing-local-signatures
warn about polymorphic local bindings without signatures
-Wmissing-local-sigs
(deprecated) warn about polymorphic local bindings without signatures
-Wmissing-methods
warn when class methods are undefined
-Wmissing-monadfail-instances
(deprecated) Warn when a failable pattern is used in a do-block that does not have
a MonadFail instance.
-Wmissing-pattern-synonym-signatures
warn when pattern synonyms do not have type signatures
-Wmissing-safe-haskell-mode
warn when the Safe Haskell mode is not explicitly specified.
-Wmissing-signatures
warn about top-level functions without signatures
-Wmissing-space-after-bang
(deprecated) Does nothing
-Wmonomorphism-restriction
warn when the Monomorphism Restriction is applied
-Wname-shadowing
warn when names are shadowed
-Wno-compat
Disables all warnings enabled by -Wcompat.
-Wnoncanonical-monad-instances
warn when Applicative or Monad instances have noncanonical definitions of return,
pure, (>>), or (*>). See flag description in Warnings and sanity-checking for more
details.
-Wnoncanonical-monadfail-instances
(deprecated) warn when Monad or MonadFail instances have noncanonical definitions
of fail.
-Wnoncanonical-monoid-instances
warn when Semigroup or Monoid instances have noncanonical definitions of (<>) or
mappend. See flag description in Warnings and sanity-checking for more details.
-Wnot (deprecated) Alias for -w
-Woperator-whitespace
warn on prefix, suffix, and tight infix uses of infix operators
-Woperator-whitespace-ext-conflict
warn on uses of infix operators that would be parsed differently were a particular
GHC extension enabled
-Worphans
warn when the module contains orphan instance declarations or rewrite rules
-Woverflowed-literals
warn about literals that will overflow their type
-Woverlapping-patterns
warn about overlapping patterns
-Wpartial-fields
warn when defining a partial record field.
-Wpartial-type-signatures
warn about holes in partial type signatures when PartialTypeSignatures is enabled.
Not applicable when PartialTypeSignatures is not enabled, in which case errors are
generated for such holes.
-Wprepositive-qualified-module
Report imports with a leading/prepositive "qualified"
-Wredundant-bang-patterns
Warn about redundant bang patterns.
-Wredundant-constraints
Have the compiler warn about redundant constraints in type signatures.
-Wredundant-record-wildcards
Warn about record wildcard matches when the wildcard binds no patterns.
-Wredundant-strictness-flags
Warn about redundant strictness flags.
-Wsafe warn if the module being compiled is regarded to be safe.
-Wsemigroup
warn when a Monoid is not Semigroup, and on non- Semigroup definitions of (<>)?
-Wsimplifiable-class-constraints
Warn about class constraints in a type signature that can be simplified using a
top-level instance declaration.
-Wstar-binder
warn about binding the (*) type operator despite StarIsType
-Wstar-is-type
warn when * is used to mean Data.Kind.Type
-Wtabs warn if there are tabs in the source file
-Wtrustworthy-safe
warn if the module being compiled is marked as Trustworthy but it could instead be
marked as Safe, a more informative bound.
-Wtype-defaults
warn when defaulting happens
-Wtype-equality-out-of-scope
warn when type equality a ~ b is used despite being out of scope
-Wtype-equality-requires-operators
warn when type equality a ~ b is used despite being out of scope
-Wtyped-holes
Report warnings when typed hole errors are deferred until runtime. See
-fdefer-typed-holes.
-Wunbanged-strict-patterns
warn on pattern bind of unlifted variable that is neither bare nor banged
-Wunicode-bidirectional-format-characters
warn about the usage of unicode bidirectional layout override characters
-Wunrecognised-pragmas
warn about uses of pragmas that GHC doesn't recognise
-Wunrecognised-warning-flags
throw a warning when an unrecognised -W... flag is encountered on the command line.
-Wunsafe
warn if the module being compiled is regarded to be unsafe. See Safe Haskell
-Wunsupported-calling-conventions
warn about use of an unsupported calling convention
-Wunsupported-llvm-version
Warn when using -fllvm with an unsupported version of LLVM.
-Wunticked-promoted-constructors
warn if promoted constructors are not ticked
-Wunused-binds
warn about bindings that are unused. Alias for -Wunused-top-binds,
-Wunused-local-binds and -Wunused-pattern-binds
-Wunused-do-bind
warn about do bindings that appear to throw away values of types other than ()
-Wunused-foralls
warn about type variables in user-written forall\s that are unused
-Wunused-imports
warn about unnecessary imports
-Wunused-local-binds
warn about local bindings that are unused
-Wunused-matches
warn about variables in patterns that aren't used
-Wunused-packages
warn when package is requested on command line, but not needed.
-Wunused-pattern-binds
warn about pattern match bindings that are unused
-Wunused-record-wildcards
Warn about record wildcard matches when none of the bound variables are used.
-Wunused-top-binds
warn about top-level bindings that are unused
-Wunused-type-patterns
warn about unused type variables which arise from patterns in in type family and
data family instances
-Wwarn make warnings non-fatal
-Wwarnings-deprecations
warn about uses of functions & types that have warnings or deprecated pragmas
-Wwrong-do-bind
warn about do bindings that appear to throw away monadic values that you should
have bound instead
COPYRIGHT
Copyright 2015. The University Court of the University of Glasgow. All rights reserved.
SEE ALSO
https://www.haskell.org/ghc the GHC homepage
AUTHOR
The GHC Team
COPYRIGHT
2024, GHC Team