Currying in OCaml

Every function takes one argument; partial application is free.

(* Every function takes one argument; more means curried. *)
let record pool species =
  Printf.sprintf "%s spotted in the %s pool" species pool

(* Partial application bakes in the first argument. *)
let at_north = record "north"

let () =
  print_endline (at_north "anemone");
  print_endline (at_north "limpet");
  print_endline (record "ledge" "sea star")

(* Annotations are legal but inference usually carries the day. *)
let quadrats (pools : int) : int = pools * 4
let () = Printf.printf "Quadrats: %d\n" (quadrats 6)

How it works

1. record pool species is two nested one-argument functions.
2. record "north" bakes in the pool and returns the rest.
3. Annotations like (pools : int) are legal; inference usually wins.

Keywords and builtins used here

• int
• let

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Step 1 of 4 in Functions, step 4 of 29 in Language basics.

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Currying in other languages

• F#