Provided by: ghc_8.0.2-11_amd64 bug


       ghc - the Glasgow Haskell Compiler


          ghc [option|filename]
          ghci [option|filename]


       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 and HTML; see below.

       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

              object files for "way" ⟨way⟩; common ways are:

              dyn    dynamically-linked

              p      built with profiling

              interface files for "way" ⟨way⟩; common ways are:


       Code generation
              -fasm  -fllvm  -fno-code -fwrite-interface -fbyte-code -fobject-code -g⟨n⟩ -dynamic

       Debugging the compiler
              -dcore-lint  -ddump-to-file  -ddump-asm  -ddump-bcos  -ddump-cmm  -ddump-core-stats
              -ddump-cse   -ddump-deriv   -ddump-ds  -ddump-foreign  -ddump-hpc  -ddump-inlinings
              -ddump-llvm -ddump-occur-anal -ddump-opt-cmm  -ddump-parsed  -ddump-prep  -ddump-rn
              -ddump-rule-firings   -ddump-rule-rewrites  -ddump-rules  -ddump-vect  -ddump-simpl
              -ddump-simpl-iterations  -ddump-spec   -ddump-splices   -ddump-stg   -ddump-stranal
              -ddump-str-signatures  -ddump-tc  -dth-dec-file  -ddump-types -ddump-worker-wrapper
              -ddump-if-trace  -ddump-tc-trace  -ddump-vt-trace  -ddump-rn-trace  -ddump-rn-stats
              -ddump-simpl-stats  -dno-debug-output  -dppr-debug  -dppr-user-length -dppr-cols⟨N⟩
              -dppr-case-as-let     -dsuppress-all      -dsuppress-uniques      -dsuppress-idinfo
              -dsuppress-unfoldings     -dsuppress-module-prefixes     -dsuppress-type-signatures
              -dsuppress-type-applications   -dsuppress-coercions    -dsource-stats    -dcmm-lint
              -dstg-lint    -dstg-stats   -dverbose-core2core   -dverbose-stg2stg   -dshow-passes
              -dfaststring-stats -frule-check

       C pre-processor
              -cpp -D⟨symbol⟩[=⟨value⟩] -U⟨symbol⟩ -I⟨dir⟩

       Finding imports
              -i ⟨dir1⟩:⟨dir2⟩:... -i

       Interactive mode
              -ignore-dot-ghci      -ghci-script      -fbreak-on-error       -fbreak-on-exception
              -fghci-hist-size=⟨n⟩           -fprint-evld-with-show           -fprint-bind-result
              -fno-print-bind-contents -fno-implicit-import-qualified -interactive-print

       Interface files
              -ddump-hi -ddump-hi-diffs -ddump-minimal-imports --show-iface ⟨file⟩

       Keeping intermediate files
              -keep-hc-file,  -keep-hc-files  -keep-llvm-file,   -keep-llvm-files   -keep-s-file,
              -keep-s-files -keep-tmp-files

       Language options
              -fconstraint-solver-iterations=⟨n⟩     -freduction-depth=⟨n⟩    -fcontext-stack=⟨n⟩
              -fglasgow-exts   -firrefutable-tuples   -fpackage-trust   -ftype-function-depth=⟨n⟩
              -XAllowAmbiguousTypes  -XArrows -XApplicativeDo -XAutoDeriveTypeable -XBangPatterns
              -XBinaryLiterals  -XCApiFFI   -XConstrainedClassMethods   -XConstraintKinds   -XCPP
              -XDataKinds      -XDefaultSignatures      -XDeriveAnyClass     -XDeriveDataTypeable
              -XDeriveFunctor  -XDeriveFoldable  -XDeriveGeneric   -XDeriveGeneric   -XDeriveLift
              -XDeriveTraversable    -XDisambiguateRecordFields    -XEmptyCase   -XEmptyDataDecls
              -XExistentialQuantification          -XExplicitForAll          -XExplicitNamespaces
              -XExtendedDefaultRules            -XFlexibleContexts            -XFlexibleInstances
              -XForeignFunctionInterface    -XFunctionalDependencies     -XGADTs     -XGADTSyntax
              -XGeneralizedNewtypeDeriving    -XGenerics   -XImplicitParams   -XNoImplicitPrelude
              -XImpredicativeTypes -XIncoherentInstances -XTypeFamilyDependencies  -XInstanceSigs
              -XInterruptibleFFI  -XKindSignatures -XLambdaCase -XLiberalTypeSynonyms -XMagicHash
              -XMonadComprehensions         -XMonoLocalBinds          -XNoMonomorphismRestriction
              -XMultiParamTypeClasses      -XMultiWayIf     -XNamedFieldPuns     -XNamedWildCards
              -XNegativeLiterals    -XNoNPlusKPatterns     -XNullaryTypeClasses     -XNumDecimals
              -XOverlappingInstances   -XOverloadedLists   -XOverloadedStrings   -XPackageImports
              -XParallelArrays   -XParallelListComp    -XPartialTypeSignatures    -XPatternGuards
              -XPatternSynonyms     -XPolyKinds     -XPolymorphicComponents    -XPostfixOperators
              -XQuasiQuotes  -XRank2Types   -XRankNTypes   -XRebindableSyntax   -XRecordWildCards
              -XRecursiveDo  -XRoleAnnotations  -XSafe -XScopedTypeVariables -XStandaloneDeriving
              -XStrictData -XTemplateHaskell -XTemplateHaskellQuotes  -XNoTraditionalRecordSyntax
              -XTransformListComp  -XTrustworthy  -XTupleSections  -XTypeFamilies -XTypeOperators
              -XTypeSynonymInstances   -XUnboxedTuples   -XUndecidableInstances   -XUnicodeSyntax
              -XUnliftedFFITypes -XUnsafe -XViewPatterns

       Linking options
              -shared  -staticlib  -fPIC  -dynload -framework⟨name⟩ -framework-path⟨name⟩ -l⟨lib⟩
              -L⟨dir⟩    -main-is    --mk-dll    -no-hs-main    -rtsopts,-rtsopts={none,some,all}
              -with-rtsopts=opts  -no-rtsopts-suggestions  -no-link  -split-objs  -split-sections
              -static -threaded -debug  -ticky  -eventlog  -fno-gen-manifest  -fno-embed-manifest
              -fno-shared-implib -dylib-install-name ⟨path⟩ -rdynamic

       Miscellaneous options
              -jN   -fno-hi-version-check   -fhistory-size   -fno-ghci-history  -fno-ghci-sandbox

       Modes of operation
              --help,-?  --interactive  --make  -e  expr  --show-iface  -M  --frontend   ⟨module⟩
              --supported-extensions,  --supported-languages  --show-options --info --version, -V
              --numeric-version --print-libdir

       Individual optimizations
              -fcall-arity  -fcase-merge  -fcmm-elim-common-blocks  -fcmm-sink  -fcpr-anal  -fcse
              -fdicts-cheap       -fdicts-strict       -fdmd-tx-dict-sel       -fdo-eta-reduction
              -fdo-lambda-eta-expansion        -feager-blackholing         -fenable-rewrite-rules
              -fexcess-precision      -fexpose-all-unfoldings      -ffloat-in     -ffull-laziness
              -ffun-to-thunk    -fignore-asserts    -fignore-interface-pragmas    -flate-dmd-anal
              -fliberate-case            -fliberate-case-threshold=⟨n⟩            -floopification
              -fmax-inline-alloc-size=⟨n⟩                           -fmax-inline-memcpy-insns=⟨n⟩
              -fmax-inline-memset-insns=⟨n⟩                              -fmax-relevant-binds=⟨n⟩
              -fmax-simplifier-iterations=⟨n⟩       -fmax-worker-args=⟨n⟩       -fno-opt-coercion
              -fno-pre-inlining     -fno-state-hack     -fomit-interface-pragmas    -fomit-yields
              -foptimal-applicative-do    -fpedantic-bottoms    -fregs-graph     -fregs-iterative
              -fsimplifier-phases=⟨n⟩            -fsimpl-tick-factor=⟨n⟩            -fspec-constr
              -fspec-constr-count=⟨n⟩          -fspec-constr-threshold=⟨n⟩           -fspecialise
              -fcross-module-specialise       -fstatic-argument-transformation       -fstrictness
              -fstrictness-before=⟨n⟩      -funbox-small-strict-fields      -funbox-strict-fields
              -funfolding-creation-threshold=⟨n⟩                    -funfolding-dict-discount=⟨n⟩
              -funfolding-fun-discount=⟨n⟩                         -funfolding-keeness-factor=⟨n⟩
              -funfolding-use-threshold=⟨n⟩         -fvectorisation-avoidance         -fvectorise

       Optimization levels
              -O0 -O, -O1 -O2 -Odph

       Package options
              -this-unit-id⟨P⟩      -package⟨P⟩      -hide-all-packages       -hide-package⟨name⟩
              -ignore-package⟨name⟩   -package-db⟨file⟩  -clear-package-db  -no-global-package-db
              -global-package-db  -no-user-package-db   -user-package-db   -no-auto-link-packages
              -trust⟨P⟩ -distrust⟨P⟩ -distrust-all

       Phases of compilation
              -F -E -C -S -c -x⟨suffix⟩

       Overriding external programs
              -pgmL⟨cmd⟩  -pgmP⟨cmd⟩  -pgmc⟨cmd⟩  -pgmlo⟨cmd⟩  -pgmlc⟨cmd⟩  -pgms⟨cmd⟩ -pgma⟨cmd⟩
              -pgml⟨cmd⟩ -pgmdll⟨cmd⟩ -pgmF⟨cmd⟩ -pgmwindres⟨cmd⟩ -pgmlibtool⟨cmd⟩

       Phase-specific options
              -optL⟨option⟩    -optP⟨option⟩    -optF⟨option⟩    -optc⟨option⟩     -optlo⟨option⟩
              -optlc⟨option⟩ -opta⟨option⟩ -optl⟨option⟩ -optdll⟨option⟩ -optwindres⟨option⟩

       Platform-specific options
              -msse2 -msse4.2

       Compiler plugins
              -fplugin=⟨module⟩ -fplugin-opt=⟨module:args⟩

              -prof      -fprof-auto     -fprof-auto-top     -fprof-auto-exported     -fprof-cafs
              -fno-prof-count-entries -ticky

       Program coverage
              -fhpc -hpcdir dir

       Recompilation checking

       Redirecting output
              -hcsuf ⟨suffix⟩ -hidir  ⟨dir⟩  -hisuf  ⟨suffix⟩  -o  ⟨filename⟩  -odir  ⟨dir⟩  -ohi
              ⟨filename⟩  -osuf  ⟨suffix⟩  -stubdir  ⟨dir⟩  -dumpdir ⟨dir⟩ -outputdir ⟨dir⟩ -dyno
              <filename> -dynosuf <suffix> -dynhisuf <suffix>

       Temporary files
              -tmpdir ⟨dir⟩

       Verbosity options
              -v        -v⟨n⟩        -fprint-potential-instances         -fprint-explicit-foralls
              -fprint-explicit-kinds     -fprint-explicit-runtime-reps     -fprint-unicode-syntax
              -fprint-expanded-synonyms       -fprint-typechecker-elaboration       -ferror-spans

              -W     -w    -Wall    -Wcompat    -Werror    -Wwarn    -Wunrecognised-warning-flags
              -fshow-warning-groups            -fdefer-type-errors            -fdefer-typed-holes
              -fdefer-out-of-scope-variables          -fhelpful-errors         -Wdeprecated-flags
              -Wduplicate-constraints     -Wduplicate-exports     -Whi-shadowing     -Widentities
              -Wimplicit-prelude          -Wincomplete-patterns         -Wincomplete-uni-patterns
              -Wmax-pmcheck-iterations=<N>      -Wincomplete-record-updates      -Wmissing-fields
              -Wmissing-import-lists            -Wmissing-methods            -Wmissing-signatures
              -Wmissing-exported-sigs     -Wmissing-exported-signatures      -Wmissing-local-sigs
              -Wmissing-local-signatures         -Wmissing-monadfail-instances        -Wsemigroup
              -Wmissed-specialisations  -Wall-missed-specialisations   -Wmonomorphism-restriction
              -Wname-shadowing  -Wnoncanonical-monad-instances -Wnoncanonical-monadfail-instances
              -Wnoncanonical-monoid-instances     -Worphans     -Woverlapping-patterns     -Wtabs
              -Wtype-defaults       -Wunrecognised-pragmas       -Wunticked-promoted-constructors
              -Wunused-binds   -Wunused-top-binds   -Wunused-local-binds   -Wunused-pattern-binds
              -Wunused-imports    -Wunused-matches    -Wunused-foralls    -Wunused-type-variables
              -Wunused-do-bind     -Wwrong-do-bind     -Wunsafe     -Wsafe     -Wtrustworthy-safe
              -Wwarnings-deprecations    -Wamp   -Wredundant-constraints   -Wdeferred-type-errors
              -Wtyped-holes      -Wdeferred-out-of-scope-variables      -Wpartial-type-signatures

   Code generation
       -fasm  Use the native code generator

       -fllvm Compile using the LLVM code generator

              Omit code generation

              Always write interface files

              Generate byte-code

              Generate object code

       -g⟨n⟩  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.

              Build dynamically-linked object files and executables

              Build dynamic object files as well as static object files during compilation

   Debugging the compiler
              Turn on internal sanity checking

              Dump to files instead of stdout

              Dump assembly

              Dump interpreter byte code

              Dump C-- output

              Print a one-line summary of the size  of  the  Core  program  at  the  end  of  the
              optimisation pipeline

              Dump CSE output

              Dump deriving output

              Dump desugarer output

              Dump foreign export stubs

              Dump after instrumentation for program coverage

              Dump inlining info

              Dump LLVM intermediate code. Implies -fllvm.

              Dump occurrence analysis output

              Dump the results of C-- to C-- optimising passes

              Dump parse tree

              Dump prepared core

              Dump renamer output

              Dump rule firing info

              Dump detailed rule firing info

              Dump rules

              Dump vectoriser input and output

              Dump final simplifier output

              Dump output from each simplifier iteration

              Dump specialiser output

              Dump TH spliced expressions, and what they evaluate to

              Dump final STG

              Dump strictness analyser output

              Dump strictness signatures

              Dump typechecker output

              Show evaluated TH declarations in a .th.hs file

              Dump type signatures

              Dump worker-wrapper output

              Trace interface files

              Trace typechecker

              Trace vectoriser

              Trace renamer

              Renamer stats

              Dump simplifier stats

              Suppress unsolicited debugging output

              Turn on debug printing (more verbose)

              Set the depth for printing expressions in error msgs

              Set the width of debugging output. For example -dppr-cols200

              Print single alternative case expressions as strict lets.

              In core dumps, suppress everything (except for uniques) that is suppressible.

              Suppress the printing of uniques in debug output (easier to use diff)

              Suppress extended information about identifiers where they are bound

              Suppress the printing of the stable unfolding of a variable at its binding site

              Suppress the printing of module qualification prefixes

              Suppress type signatures

              Suppress type applications

              Suppress the printing of coercions in Core dumps to make them shorter

              Dump haskell source stats

              C-- pass sanity checking

              STG pass sanity checking

              Dump STG stats

              Show output from each core-to-core pass

              Show output from each STG-to-STG pass

              Print out each pass name as it happens

              Show statistics for fast string usage when finished

              Report sites with rules that could have fired but didn't. Takes a string argument.

   C pre-processor
       -cpp   Run the C pre-processor on Haskell source files

              Define a symbol in the C pre-processor

              Undefine a symbol in the C pre-processor

              Add ⟨dir⟩ to the directory search list for #include files

   Finding imports
       -i ⟨dir1⟩:⟨dir2⟩:...
              add ⟨dir⟩, ⟨dir2⟩, etc. to import path

       -i     Empty the import directory list

   Interactive mode
              Disable reading of .ghci files

              Read additional .ghci files

              Break on uncaught exceptions and errors

              Break on any exception thrown

              Set the number of entries GHCi keeps for :history. See ghci-debugger.

              Enable usage of Show instances in :print. See breakpoints.

              Turn on printing of binding results in GHCi

              Turn off printing of binding contents in GHCi

              Turn off implicit qualified import of everything in GHCi

              Select the function to use for printing evaluated expressions in GHCi

   Interface files
              Dump the new interface to stdout

              Show the differences vs. the old interface

              Dump a minimal set of imports

       --show-iface ⟨file⟩
              See modes.

   Keeping intermediate files
       -keep-hc-file, -keep-hc-files
              Retain intermediate .hc files.

       -keep-llvm-file, -keep-llvm-files
              Retain intermediate LLVM .ll files. Implies -fllvm.

       -keep-s-file, -keep-s-files
              Retain intermediate .s files.

              Retain all intermediate temporary files.

   Language options
              default:  4.  Set the iteration limit for the type-constraint solver. Typically one
              iteration suffices; so please yell if you find you need to set it higher  than  the
              default. Zero means infinity.

              default: 200. Set the limit for type simplification. Zero means infinity.

              Deprecated. Use -freduction-depth=⟨n⟩ instead.

              Deprecated. Enable most language extensions; see options-language for exactly which

              Make tuple pattern matching irrefutable

              Enable Safe Haskell trusted package requirement for trustworthy modules.

              Deprecated. Use -freduction-depth=⟨n⟩ instead.

              Allow the user to write ambiguous types, and the type  inference  engine  to  infer

              Enable arrow notation extension

              Enable Applicative do-notation desugaring

              As  of GHC 7.10, this option is not needed, and should not be used. Previously this
              would automatically derive Typeable instances for every  datatype  and  type  class
              declaration. Implies -XDeriveDataTypeable.

              Enable bang patterns.

              Enable support for binary literals.

              Enable the CAPI calling convention.

              Enable constrained class methods.

              Enable a kind of constraints.

       -XCPP  Enable the C preprocessor.

              Enable datatype promotion.

              Enable default signatures.

              Enable deriving for any class.

              Enable deriving for the Data class. Implied by -XAutoDeriveTypeable.

              Enable deriving for the Functor class. Implied by -XDeriveTraversable.

              Enable deriving for the Foldable class. Implied by -XDeriveTraversable.

              Enable deriving for the Generic class.

              Enable deriving for the Generic class.

              Enable deriving for the Lift class

              Enable   deriving   for   the   Traversable   class.  Implies  -XDeriveFunctor  and

              Enable record field disambiguation. Implied by -XRecordWildCards.

              Allow empty case alternatives.

              Enable empty data declarations.

              Enable existential quantification.

              Enable  explicit  universal  quantification.  Implied   by   -XScopedTypeVariables,
              -XLiberalTypeSynonyms, -XRankNTypes and -XExistentialQuantification.

              Enable  using  the  keyword type to specify the namespace of entries in imports and
              exports (explicit-namespaces). Implied by -XTypeOperators and -XTypeFamilies.

              Use GHCi's extended default rules in a normal module.

              Enable flexible contexts. Implied by -XImplicitParams.

              Enable   flexible   instances.   Implies   -XTypeSynonymInstances.    Implied    by

              Enable foreign function interface.

              Enable functional dependencies. Implies -XMultiParamTypeClasses.

              Enable generalised algebraic data types. Implies -XGADTSyntax and -XMonoLocalBinds.

              Enable generalised algebraic data type syntax.

              Enable newtype deriving.

              Deprecated, does nothing. No longer enables generic classes. See also GHC's support
              for generic programming.

              Enable Implicit Parameters. Implies -XFlexibleContexts and -XFlexibleInstances.

              Don't implicitly import Prelude. Implied by -XRebindableSyntax.

              Enable impredicative types. Implies -XRankNTypes.

              Enable incoherent instances. Implies -XOverlappingInstances.

              Enable injective type families. Implies -XTypeFamilies.

              Enable instance signatures.

              Enable interruptible FFI.

              Enable kind signatures. Implied by -XTypeFamilies and -XPolyKinds.

              Enable lambda-case expressions.

              Enable liberalised type synonyms.

              Allow # as a postfix modifier on identifiers.

              Enable monad comprehensions.

              Enable do not generalise local bindings. Implied by -XTypeFamilies and -XGADTs.

              Disable the monomorphism restriction.

              Enable multi parameter type classes. Implied by -XFunctionalDependencies.

              Enable multi-way if-expressions.

              Enable record puns.

              Enable named wildcards.

              Enable support for negative literals.

              Disable support for n+k patterns.

              Deprecated, does nothing. nullary (no parameter) type classes are now enabled using

              Enable support for 'fractional' integer literals.

              Enable overlapping instances.

              Enable overloaded lists.

              Enable overloaded string literals.

              Enable package-qualified imports.

              Enable parallel arrays. Implies -XParallelListComp.

              Enable parallel list comprehensions. Implied by -XParallelArrays.

              Enable partial type signatures.

              Enable pattern guards.

              Enable pattern synonyms.

              Enable kind polymorphism. Implies -XKindSignatures.

              Enable polymorphic components for data constructors. Synonym for -XRankNTypes.

              Enable postfix operators.

              Enable quasiquotation.

              Enable rank-2 types. Synonym for -XRankNTypes.

              Enable rank-N types. Implied by -XImpredicativeTypes.

              Employ rebindable syntax. Implies -XNoImplicitPrelude.

              Enable record wildcards. Implies -XDisambiguateRecordFields.

              Enable recursive do (mdo) notation.

              Enable role annotations.

       -XSafe Enable the Safe Haskell Safe mode.

              Enable lexically-scoped type variables.

              Enable standalone deriving.

              Enable default strict datatype fields.

              Enable Template Haskell.

              Enable quotation subset of Template Haskell.

              Disable  support  for traditional record syntax (as supported by Haskell 98) C {f =

              Enable generalised list comprehensions.

              Enable the Safe Haskell Trustworthy mode.

              Enable tuple sections.

              Enable  type  families.   Implies   -XExplicitNamespaces,   -XKindSignatures,   and

              Enable type operators. Implies -XExplicitNamespaces.

              Enable type synonyms in instance heads. Implied by -XFlexibleInstances.

              Enable unboxed tuples.

              Enable undecidable instances.

              Enable unicode syntax.

              Enable unlifted FFI types.

              Enable Safe Haskell Unsafe mode.

              Enable view patterns.

   Linking options
              Generate a shared library (as opposed to an executable)

              On  Darwin/OS  X/iOS  only,  generate a standalone static library (as opposed to an
              executable). This is the usual way to compile for iOS.

       -fPIC  Generate position-independent code (where available)

              Selects one of a number of modes for finding shared libraries at runtime.

              On Darwin/OS X/iOS only, link in the framework ⟨name⟩. This option  corresponds  to
              the -framework option for Apple's Linker.

              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.

              Link in library ⟨lib⟩

              Add ⟨dir⟩ to the list of directories searched for libraries

              Set main module and function

              DLL-creation mode (Windows only)

              Don't assume this program contains main

              Control whether the RTS behaviour can be  tweaked  via  command-lineflags  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), and all (or no  argument
              at all) means that all RTS flags are permitted.

              Set the default RTS options to ⟨opts⟩.

              Don't print RTS suggestions about linking with -rtsopts.

              Omit linking

              Split objects (for libraries)

              Split sections for link-time dead-code stripping

              Use static Haskell libraries

              Use the threaded runtime

       -debug Use the debugging runtime

       -ticky For linking, this simply implies -debug; see ticky-ticky.

              Enable runtime event tracing

              Do not generate a manifest file (Windows only)

              Do not embed the manifest in the executable (Windows only)

              Don't generate an import library for a DLL (Windows only)

       -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)

              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.

   Miscellaneous options
       -jN    When compiling with --make, compile ⟨N⟩ modules in parallel.

              Don't complain about .hi file mismatches

              Set simplification history size

              Do not use the load/store the GHCi command history from/to ghci_history.

              Turn off the GHCi sandbox. Means computations are run in the  main  thread,  rather
              than a forked thread.

              Display errors in GHC/GHCi sorted by reverse order of source code line numbers.

   Modes of operation
              Display help

              Interactive mode - normally used by just running ghci; see 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 make-mode for details.

       -e expr
              Evaluate expr; see eval-mode for details.

              display the contents of an interface file.

       -M     generate  dependency  information   suitable   for   use   in   a   Makefile;   see
              makefile-dependencies for details.

       --frontend ⟨module⟩
              run GHC with the given frontend plugin; see frontend_plugins for details.

       --supported-extensions, --supported-languages
              display the supported language extensions

              display the supported command line options

       --info display information about the compiler

       --version, -V
              display GHC version

              display GHC version (numeric only)

              display GHC library directory

   Individual optimizations
              Enable call-arity optimisation. Implied by -O.

              Enable case-merging. Implied by -O.

              Enable Cmm common block elimination. Implied by -O.

              Enable Cmm sinking. Implied by -O.

              Turn on CPR analysis in the demand analyser. Implied by -O.

       -fcse  Enable common sub-expression elimination. Implied by -O.

              Make dictionary-valued expressions seem cheap to the optimiser.

              Make dictionaries strict

              Use  a  special  demand  transformer  for  dictionary  selectors. Always enabled by

              Enable eta-reduction. Implied by -O.

              Enable lambda eta-expansion. Always enabled by default.

              Turn on eager blackholing

              Switch on all rewrite rules (including rules generated by automatic  specialisation
              of overloaded functions). Implied by -O.

              Enable excess intermediate precision

              Expose all unfoldings, even for very large or recursive functions.

              Turn on the float-in transformation. Implied by -O.

              Turn on full laziness (floating bindings outwards). Implied by -O.

              Allow  worker-wrapper  to  convert  a function closure into a thunk if the function
              does not use any of its arguments. Off by default.

              Ignore assertions in the source. Implied by -O.

              Ignore pragmas in interface files. Implied by -O0 only.

              Run demand analysis again, at the end of the simplification pipeline

              Turn on the liberate-case transformation. Implied by -O2.

              default: 2000. Set the size threshold for the liberate-case transformation to ⟨n⟩

              Turn  saturated  self-recursive  tail-calls  into  local  jumps  in  the  generated
              assembly. Implied by -O.

              default:  128.  Set  the  maximum  size  of  inline  array allocations to ⟨n⟩ bytes
              (default: 128). GHC will allocate non-pinned arrays of statically known size in the
              current  nursery  block  if they're no bigger than ⟨n⟩ bytes, ignoring GC overheap.
              This value should be quite a bit smaller than the block size (typically: 4096).

              default: 32. Inline memcpy calls if they would generate no  more  than  ⟨n⟩  pseudo

              default:  32.  Inline  memset  calls if they would generate no more than ⟨n⟩ pseudo

              default: 6. Set the maximum number of bindings to display in type error messages.

              default: 4. Set the max iterations for the simplifier.

              default: 10. If a worker has that many arguments, none will be unpacked anymore.

              Turn off the coercion optimiser

              Turn off pre-inlining

              Turn off the "state hack" whereby any lambda  with  a  real-world  state  token  as
              argument is considered to be single-entry. Hence OK to inline things inside it.

              Don't generate interface pragmas. Implied by -O0 only.

              Omit heap checks when no allocation is being performed.

              Use a slower but better algorithm for ApplicativeDo

              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.

              Use the graph colouring register allocator for register allocation  in  the  native
              code generator. Implied by -O2.

              Use  the iterative coalescing graph colouring register allocator in the native code

              default: 2. Set the number of phases for the simplifier. Ignored with -O0.

              default: 100. Set the percentage factor for simplifier ticks.

              Turn on the SpecConstr transformation. Implied by -O2.

              default: 3.* Set to ⟨n⟩ the maximum number of specialisations that will be  created
              for any one function by the SpecConstr transformation.

              default: 2000. Set the size threshold for the SpecConstr transformation to ⟨n⟩.

              Turn on specialisation of overloaded functions. Implied by -O.

              Turn on specialisation of overloaded functions imported from other modules.

              Turn on the static argument transformation.

              Turn on strictness analysis. Implied by -O. Implies -fworker-wrapper

              Run an additional strictness analysis before simplifier phase ⟨n⟩

              Flatten  strict  constructor fields with a pointer-sized representation. Implied by

              Flatten strict constructor fields

              default: 750. Tweak unfolding settings.

              default: 30. Tweak unfolding settings.

              default: 60. Tweak unfolding settings.

              default: 1.5. Tweak unfolding settings.

              default: 60. Tweak unfolding settings.

              Enable vectorisation avoidance. Always enabled by default.

              Enable vectorisation of nested data parallelism

              Enable the worker-wrapper transformation after a strictness analysis pass.  Implied
              by  -O, and by -fstrictness. Disabled by -fno-strictness. Enabling -fworker-wrapper
              while strictness analysis is disabled (by -fno-strictness) has no effect.

   Optimization levels
       -O0    Disable optimisations (default)

       -O, -O1
              Enable level 1 optimisations

       -O2    Enable level 2 optimisations

       -Odph  Enable   level   2   optimisations,    set    -fmax-simplifier-iterations=20    and

   Package options
              Compile to be part of unit (i.e. package) ⟨P⟩

              Expose package ⟨P⟩

              Hide all packages by default

              Hide package ⟨P⟩

              Ignore package ⟨P⟩

              Add ⟨file⟩ to the package db stack.

              Clear the package db stack.

              Remove the global package db from the stack.

              Add the global package db to the stack.

              Remove the user's package db from the stack.

              Add the user's package db to the stack.

              Don't automatically link in the base and rts packages.

              Expose package ⟨P⟩ and set it to be trusted

              Expose package ⟨P⟩ and set it to be distrusted

              Distrust all packages by default

   Phases of compilation
       -F     Enable the use of a pre-processor (set with -pgmF)

       -E     Stop after preprocessing (.hspp file)

       -C     Stop after generating C (.hc file)

       -S     Stop after generating assembly (.s file)

       -c     Stop after generating object (.o) file

              Override default behaviour for source files

   Overriding external programs
              Use ⟨cmd⟩ as the literate pre-processor

              Use ⟨cmd⟩ as the C pre-processor (with -cpp only)

              Use ⟨cmd⟩ as the C compiler

              Use ⟨cmd⟩ as the LLVM optimiser

              Use ⟨cmd⟩ as the LLVM compiler

              Use ⟨cmd⟩ as the splitter

              Use ⟨cmd⟩ as the assembler

              Use ⟨cmd⟩ as the linker

              Use ⟨cmd⟩ as the DLL generator

              Use ⟨cmd⟩ as the pre-processor (with -F only)

              Use ⟨cmd⟩ as the program for embedding manifests on Windows.

              Use ⟨cmd⟩ as the command for libtool (with -staticlib only).

   Phase-specific options
              pass ⟨option⟩ to the literate pre-processor

              pass ⟨option⟩ to cpp (with -cpp only)

              pass ⟨option⟩ to the custom pre-processor

              pass ⟨option⟩ to the C compiler

              pass ⟨option⟩ to the LLVM optimiser

              pass ⟨option⟩ to the LLVM compiler

              pass ⟨option⟩ to the assembler

              pass ⟨option⟩ to the linker

              pass ⟨option⟩ to the DLL generator

              pass ⟨option⟩ to windres.

   Platform-specific options
       -msse2 (x86 only) Use SSE2 for floating-point operations

              (x86 only) Use SSE4.2 for floating-point operations

   Compiler plugins
              Load a plugin exported by a given module

              Give arguments to a plugin module; module must be specified with -fplugin

       -prof  Turn on profiling

              Auto-add SCCs to all bindings not marked INLINE

              Auto-add SCCs to all top-level bindings not marked INLINE

              Auto-add SCCs to all exported bindings not marked INLINE

              Auto-add SCCs to all CAFs

              Do not collect entry counts

       -ticky Turn on ticky-ticky profiling

   Program coverage
       -fhpc  Turn on Haskell program coverage instrumentation

       -hpcdir dir
              Directory to deposit .mix files during compilation (default is .hpc)

   Recompilation checking
              Turn  off  recompilation  checking.  This  is  implied  by any -ddump-X option when
              compiling a single file (i.e. when using -c).

   Redirecting output
       -hcsuf ⟨suffix⟩
              set the suffix to use for intermediate C files

       -hidir ⟨dir⟩
              set directory for interface files

       -hisuf ⟨suffix⟩
              set the suffix to use for interface files

       -o ⟨filename⟩
              set output filename

       -odir ⟨dir⟩
              set directory for object files

       -ohi ⟨filename⟩
              set the filename in which to put the interface

       -osuf ⟨suffix⟩
              set the output file suffix

       -stubdir ⟨dir⟩
              redirect FFI stub files

       -dumpdir ⟨dir⟩
              redirect dump files

       -outputdir ⟨dir⟩
              set output directory

       -dyno <filename>
              Set the output filename for dynamic object files (see -dynamic-too)

       -dynosuf <suffix>
              Set the object suffix for dynamic object files (see -dynamic-too)

       -dynhisuf <suffix>
              Set the hi suffix for dynamic object files (see -dynamic-too)

   Temporary files
       -tmpdir ⟨dir⟩
              set the directory for temporary files

   Verbosity options
       -v     verbose mode (equivalent to -v3)

       -v⟨n⟩  set verbosity level

              display all available instances in type error messages

              Print explicit forall quantification in types. See also -XExplicitForAll

              Print explicit kind foralls and kind arguments in types. See also -XKindSignature

              Print RuntimeRep variables in types which are runtime-representation polymorphic.

              Use  unicode  syntax  when  printing  expressions,  types  and  kinds.   See   also

              In type errors, also print type-synonym-expanded types.

              Print extra information from typechecker.

              Output full span in error messages

              Summarise timing stats for GHC (same as +RTS -tstderr).

       -W     enable normal warnings

       -w     disable all warnings

       -Wall  enable almost all warnings (details in options-sanity)

              enable future compatibility warnings (details in options-sanity)

              make warnings fatal

       -Wwarn make warnings non-fatal

              throw a warning when an unreconised -W... flag is encountered on the command line.

              show which group an emitted warning belongs to.

              Turn  type  errors  into  warnings,  deferring  the  error  until  runtime. Implies
              -fdefer-typed-holes     and      -fdefer-out-of-scope-variables.      See      also

              Convert typed hole errors into warnings, deferring the error until runtime. Implied
              by -fdefer-type-errors. See also -Wtyped-holes.

              Convert  variable  out  of  scope  variables  errors  into  warnings.  Implied   by
              -fdefer-type-errors. See also -Wdeferred-out-of-scope-variables.

              Make suggestions for mis-spelled names.

              warn about uses of commandline flags that are deprecated

              warn when a constraint appears duplicated in a type signature

              warn when an entity is exported multiple times

              warn when a .hi file in the current directory shadows a library

              warn  about uses of Prelude numeric conversions that are probably the identity (and
              hence could be omitted)

              warn when the Prelude is implicitly imported

              warn when a pattern match could fail

              warn when a pattern match in a lambda expression or pattern binding could fail

              the iteration limit for the pattern match checker

              warn when a record update could fail

              warn when fields of a record are uninitialised

              warn when an import declaration does not explicitly list all thenames brought  into

              warn when class methods are undefined

              warn about top-level functions without signatures

              (deprecated)  warn  about  top-level functions without signatures, only if they are
              exported. takes precedence over -Wmissing-signatures

              warn about top-level functions without signatures, only if they are exported. takes
              precedence over -Wmissing-signatures

              (deprecated) warn about polymorphic local bindings without signatures

              warn about polymorphic local bindings without signatures

              warn  when  a failable pattern is used in a do-block that does not have a MonadFail

              warn when a Monoid is not Semigroup, and on non-Semigroup definitions of (<>)?

              warn when specialisation of an imported, overloaded function fails.

              warn when specialisation of any overloaded function fails.

              warn when the Monomorphism Restriction is applied

              warn when names are shadowed

              warn when Applicative or Monad instances have noncanonical definitions  of  return,
              pure, (>>), or (*>). See flag description in options-sanity for more details.

              warn  when  Monad  or MonadFail instances have noncanonical definitions of fail.See
              flag description in options-sanity for more details.

              warn when Semigroup or Monoid instances have noncanonical definitions  of  (<>)  or
              mappend. See flag description in options-sanity for more details.

              warn when the module contains orphan instance declarations or rewrite rules

              warn about overlapping patterns

       -Wtabs warn if there are tabs in the source file

              warn when defaulting happens

              warn about uses of pragmas that GHC doesn't recognise

              warn if promoted constructors are not ticked

              warn    about   bindings   that   are   unused.   Alias   for   -Wunused-top-binds,
              -Wunused-local-binds and -Wunused-pattern-binds

              warn about top-level bindings that are unused

              warn about local bindings that are unused

              warn about pattern match bindings that are unused

              warn about unnecessary imports

              warn about variables in patterns that aren't used

              warn about type variables in user-written foralls that are unused

              warn about variables in type family or data family instances that are unused

              warn about do bindings that appear to throw away values of types other than ()

              warn about do bindings that appear to throw away monadic  values  that  you  should
              have bound instead

              warn if the module being compiled is regarded to be unsafe. Should be used to check
              the safety status of modules when using safe inference. Works on all module  types,
              even  those using explicit Safe Haskell modes (such as -XTrustworthy) and so can be
              used to have the compiler check any assumptions made.

       -Wsafe warn if the module being compiled is regarded to be safe. Should be used  to  check
              the  safety status of modules when using safe inference. Works on all module types,
              even those using explicit Safe Haskell modes (such as -XTrustworthy) and so can  be
              used to have the compiler check any assumptions made.

              warn  if  the module being compiled is marked as -XTrustworthy but it could instead
              be marked as -XSafe, a more informative bound. Can be used  to  detectonce  a  Safe
              Haskell bound can be improved as dependencies are updated.

              warn about uses of functions & types that have warnings or deprecated pragmas

       -Wamp  (deprecated)  warn  on  definitions conflicting with the Applicative-Monad Proposal

              Have the compiler warn about redundant constraints in typesignatures.

              Report warnings when deferred type errors are enabled. This option  is  enabled  by
              default. See -fdefer-type-errors.

              Report   warnings   when   typed  hole  errors  are  deferred  until  runtime.  See

              Report warnings when variable out-of-scope errors are deferred until  runtime.  See

              warn  about  holes  in  partial  type  signatures  when  -XPartialTypeSignatures is
              enabled. Not applicable when -XPartialTypesignatures is not enabled, in which  case
              errors are generated for such holes. See partial-type-signatures.

              warn when encountering a request to derive an instance of class Typeable. As of GHC
              7.10, such declarations are unnecessary and are ignored by the compiler because GHC
              has a custom solver for discharging this type of constraint.


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       The GHC Team


       2018, GHC Team