F# explicit match vs function syntax

Question

Sorry about the vague title, but part of this question is what these two syntax styles are called:

let foo1 x = 
    match x with
    | 1 -> "one"
    | _ -> "not one"

let foo2 = function 
    | 1 -> "one" 
    | _ -> "not one"

The other part is what difference there is between the two, and when I would want to use one or the other?

user_453596 · Answer

function only allows for one argument but allows for pattern matching, while fun is the more general and flexible way to define a function. Take a look here: http://caml.inria.fr/pub/docs/manual-ocaml/expr.html