Difference between revisions of "OCaml"
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match x with |
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− | B x when x > 0 -> ... |
+ | B x when x > 0 -> ... |
− | C (a, b) -> ... |
+ | | C (a, b) -> ... |
| There doesn't seem to be syntax for multiple guards |
| There doesn't seem to be syntax for multiple guards |
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Revision as of 13:22, 12 December 2012
OCaml is a functional programming language in the ML family, an extension of the Caml language with object-oriented constructs.
This page aims to cover some of its differences from Haskell.
Syntactic dictionary
Haskell | OCaml | Comments | ||
Anonymous functions |
\x y -> ... |
fun x y -> ... |
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Multiple assignments |
let x = 4 y = 5 in ... |
let x = 4 and y = 5 in ... |
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Types |
Int, Bool, (Double, Char), a |
int, bool, float * char, 'a |
float is a double type | |
Type signatures |
const :: a -> b -> a |
const : 'a -> 'b -> 'a |
Signatures usually omitted in OCaml | |
Type declarations |
data A = B Int | C Char Bool x = B 3 y = C 'a' True |
type a = B of int | C of char * bool let x = B 3 and y = C ('a', true) |
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Parametrised types |
data D a = D (a -> a) data E a b = L a | R b |
type 'a d = D of ('a -> 'a) type ('a, 'b) e = L of 'a | R of 'b | ||
Pattern matching |
case x of A x | x > 0 -> ... C a b -> ... |
match x with B x when x > 0 -> ... |
C (a, b) -> ... | There doesn't seem to be syntax for multiple guards |
Conceptual differences
OCaml is strict by default, although it has some facility for introducing laziness.
OCaml's let is non-recursive by default, but has the form let rec for defining recursive functions.
OCaml is impure: although it makes heavy use of immutable data, it also has mutable references and arrays available, and IO is performed by ordinary functions.