focal (3) Fun.3o.gz

NAME

       Fun - Function manipulation.

Module

       Module   Fun

Documentation

       Module Fun
        : sig end

       Function manipulation.

       Since 4.08

   Combinators
       val id : 'a -> 'a

       id is the identity function. For any argument x , id x is x .

       val const : 'a -> 'b -> 'a

       const c is a function that always returns the value c . For any argument x , (const c) x is c .

       val flip : ('a -> 'b -> 'c) -> 'b -> 'a -> 'c

       flip f reverses the argument order of the binary function f . For any arguments x and y , (flip f) x y is
       f y x .

       val negate : ('a -> bool) -> 'a -> bool

       negate p is the negation of the predicate function p . For any argument x , (negate p) x is not (p x) .

   Exception handling
       val protect : finally:(unit -> unit) -> (unit -> 'a) -> 'a

       protect ~finally work invokes work () and then finally () before work () returns with  its  value  or  an
       exception.  In  the  latter  case  the  exception is re-raised after finally () . If finally () raises an
       exception, then the exception Fun.Finally_raised is raised instead.

       protect can be used to enforce local invariants whether work () returns normally or raises an  exception.
       However, it does not protect against unexpected exceptions raised inside finally () such as Out_of_memory
       , Stack_overflow , or asynchronous exceptions raised by signal handlers (e.g.  Sys.Break ).

       Note: It is a programming error if other kinds of exceptions are raised by finally  ,  as  any  exception
       raised in work () will be lost in the event of a Fun.Finally_raised exception. Therefore, one should make
       sure to handle those inside the finally.

       exception Finally_raised of exn

       Finally_raised exn is raised by protect ~finally work  when  finally  raises  an  exception  exn  .  This
       exception  denotes  either  an unexpected exception or a programming error. As a general rule, one should
       not catch a Finally_raised exception except as part of a catch-all handler.