[Caml-list] Applying labeled function without a label

[Ivan Gotovchits <ivg@ieee.org>]

Please, can someone explain the reason behind the following behaviour:


# let f ~a = a;;
val f : a:'a -> 'a = <fun>

if I apply function f, omiting the label, instead of an error I'll get:

# f 12;;
- : a:(int -> 'a) -> 'a = <fun>

... a function that accepts a labeled arguments, that is a function from int
to 'a, and returns a result of this function:

# f 12 ~a:(fun x -> x + 1);;
- : int = 13

and even more, if I apply it to more unlabled arguments:

# f 1 2 3 4 5;;
- : a:(int -> int -> int -> int -> int -> 'a) -> 'a = <fun>

It is very confusing...