Module CCFun

Basic operations on Functions

val id : 'a -> 'a
val const : 'a -> 'b -> 'a
val flip : ('a -> 'b -> 'c) -> 'b -> 'a -> 'c
val negate : ('a -> bool) -> 'a -> bool
val protect : finally:(unit -> unit) -> (unit -> 'a) -> 'a
exception Finally_raised of exn
val and_pred : ('a -> bool) -> ('a -> bool) -> 'a -> bool

and_p f g x is (f x) && (g x). Produces a predicate which is a conjunction of the two predicates.

  • since 3.13.1
val or_pred : ('a -> bool) -> ('a -> bool) -> 'a -> bool

or_p f g x is (f x) || (g x). Produces a predicate which is a disjunction of the two predicates.

  • since 3.13.1
val compose : ('a -> 'b) -> ('b -> 'c) -> 'a -> 'c

compose f g x is g (f x). Composition.

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

compose_binop f g is fun x y -> g (f x) (f y). Example (partial order): List.sort (compose_binop fst CCInt.compare) [1, true; 2, false; 1, false].

  • since 0.6
val curry : (('a * 'b) -> 'c) -> 'a -> 'b -> 'c

curry f x y is f (x,y). Convert a function which accepts a pair of arguments into a function which accepts two arguments.

val uncurry : ('a -> 'b -> 'c) -> ('a * 'b) -> 'c

uncurry f (x,y) is f x y. Convert a function which accepts a two arguments into a function which accepts a pair of arguments.

val tap : ('a -> _) -> 'a -> 'a

tap f x evaluates f x, discards it, then returns x. Useful in a pipeline, for instance:

CCArray.(1 -- 10)
|> tap CCArray.shuffle
|> tap @@ CCArray.sort Stdlib.compare
val lexicographic : ('a -> 'a -> int) -> ('a -> 'a -> int) -> 'a -> 'a -> int

Lexicographic combination of comparison functions.

val finally : h:(unit -> _) -> f:(unit -> 'a) -> 'a

finally ~h f calls f () and returns its result. If it raises, the same exception is raised; in any case, h () is called after f () terminates. If h () raises an exception, then this exception will be passed on and any exception that may have been raised by f () is lost.

val finally1 : h:(unit -> _) -> ('a -> 'b) -> 'a -> 'b

finally1 ~h f x is the same as f x, but after the computation, h () is called whether f x rose an exception or not. If h () raises an exception, then this exception will be passed on and any exception that may have been raised by f () is lost.

  • since 0.16
val finally2 : h:(unit -> _) -> ('a -> 'b -> 'c) -> 'a -> 'b -> 'c

finally2 ~h f x y is the same as f x y, but after the computation, h () is called whether f x y rose an exception or not. If h () raises an exception, then this exception will be passed on and any exception that may have been raised by f () is lost.

  • since 0.16
val opaque_identity : 'a -> 'a

opaque_identity x is like x, but prevents Flambda from using x's definition for optimizing it. (flambda is an optimization/inlining pass in OCaml >= 4.03).

  • since 0.18
val iterate : int -> ('a -> 'a) -> 'a -> 'a

iterate n f is f iterated n times. That is to say, iterate 0 f x is x, iterate 1 f x is f x, iterate 2 f x is f (f x), etc.

  • since 2.1

Infix

Infix operators.

module Infix : sig ... end
include module type of Infix
val (%>) : ('a -> 'b) -> ('b -> 'c) -> 'a -> 'c

(f %> g) x or (%>) f g x is g (f x). Alias to compose.

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

(f % g) x or (%) f g x is f (g x). Mathematical composition.

val let@ : ('a -> 'b) -> 'a -> 'b

let@ x = foo in bar is the equivalent of foo @@ fun x -> bar. It can be very useful for resource management, alongside with protect.

  • since 3.11
val (||>) : ('a * 'b) -> ('a -> 'b -> 'c) -> 'c

x ||> f is f (fst x) (snd x)

  • since 3.13.1
val (|||>) : ('a * 'b * 'c) -> ('a -> 'b -> 'c -> 'd) -> 'd

like ||> but for tuples of size 3

  • since 3.13.1

Monad

Functions with a fixed domain are monads in their codomain.

module Monad (X : sig ... end) : sig ... end