CODEWITHSUNDEEP
functional-programmingocaml
measuretheory
measuretheory

Reputation: 117

Curious about behaving of OCaml

I have a question why does OCaml behaves somewhat unusual. By defining the function

let abs_diff x y = abs(x - y);;

we get val abs_diff : int -> int -> int = <fun> now by defining as

let abs_diff x y = fun x -> (fun y -> abs(x - y));;

val abs_diff : 'a -> 'b -> int -> int -> int = <fun>

now using another function called as

let dist_from3 = abs_diff 3;;

with the first definition it works perfectly but with the second one it does not work as expected. We get that it is

val dist_from3 : '_a -> int -> int -> int = <fun>

why is it behaving like that, and why are those two definition of the at first look same function different?

Upvotes: 1

Views: 52

Answers (1)

Jeffrey Scofield
Jeffrey Scofield

Reputation: 66818

In your second definition you have two distinct appearances (bindings) of x and y. That's why there are four parameters in the result. This is what you want:

let abs_diff = fun x -> fun y -> abs (x - y)

(FWIW in actual practice I sometimes make this mistake, especially when using the function keyword.)

Upvotes: 5

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