package travesty

  1. Overview
  2. Docs
package travesty
Legend:
Library
Module
Module type
Parameter
Class
Class type

Miscellaneous function combinators.

Fn contains various higher-order functions in the style of Base's Fn module.

Constant predicates

These are convenience shorthands for Base.Fn.const.

val always : 'a -> bool

always x is true.

val never : 'a -> bool

never x is false.

Pointwise liftings of operators

These complement Base.Fn.non.

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

conj f g lifts && over predicates f and g. It is short-circuiting: g is never called if f returns false.

Examples:

let is_zero = Int.(conj is_non_negative is_non_positive)
(* Short-circuiting: *)
conj always (fun () -> failwith "oops") (); (* --> exception *)
conj never  (fun () -> failwith "oops") (); (* --> false *)
val disj : ('a -> bool) -> ('a -> bool) -> 'a -> bool

disj f g lifts || over predicates f and g. It is short-circuiting: g is never called if f returns true.

Examples:

let is_not_zero = Int.(disj is_negative is_positive)
(* Short-circuiting: *)
disj never  (fun () -> failwith "oops") (); (* --> exception *)
disj always (fun () -> failwith "oops") (); (* --> false *)
val (&&&) : ('a -> bool) -> ('a -> bool) -> 'a -> bool

f &&& g is conj f g.

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

f ||| g is disj f g.

Miscellaneous combinators

val on : ('a -> 'b) -> 'a -> 'a -> f:('b -> 'b -> 'r) -> 'r

on lift x y ~f lifts a binary function f using the lifter lift. It does the same thing as the `on` function from Haskell, but with arguments flipped to make sense without infixing.

Effectively, it's Base.Comparable.lift, but with a slightly different signature.

Example:

let ints = on fst    ~f:Int.equal (42, "banana") (42, "apple") in
let strs = on snd ~f:String.equal (42, "banana") (42, "apple") in
ints, strs (* --> true, false *)

F# style function composition operator

This is in a separate module to reduce the ambiguity caused by its use.

module Compose_syntax : sig ... end
OCaml

Innovation. Community. Security.

GitHub Discord Twitter Peertube RSS
About
Changelog Releases Industrial Users Academic Users Why OCaml
Ecosystem
Packages Community Events OCaml Planet Jobs
Resources
Install OCaml Get Started Platform Tools Language Manual Standard Library API Books Exercises Papers OCaml Playground Logo
Policies
Carbon Footprint Governance Privacy Code of Conduct