Syntax missed opporunities, or else?

Hi when binding a value with explicit type we use

let x:float = 1

so this to me says, x returns a float
but when binding a function we use

let add (x:float) (y:float) :float = x + y

when I honestly first guessed the syntax to be

let add:float x:float y:float = x+y

obviously this wont work, but it looks nice and seem more inuitive , why was the former syntax chosen over the later
(note also the syntax let add x:float y:float :float = x + y dont work you need the brackets

1 Like

That particular syntax was brought over from OCaml, so probably nobody building F# was ever involved in that decision. It might be hard to track down the roots of that decision when it was made for OCaml.

That said, I tend to like the syntax as it is, so I have a guess why that decision was made. I like it mainly because I often look at and think about functions in terms of their type signature. So if I have

let fn (x:string) (y:int) : float = ...

I find it very natural that the type signature is fn : string -> int -> float.
If fn was defined as

let fn:float x:string y:int = ...

it would be a little roundabout to have fn : string -> int -> float. It would just take more mental gymnastics on my part.

Ultimately though I think it’s just a preference thing. There are perfectly valid reasons why someone would prefer the syntax that you proposed, and perfectly valid reasons someone would prefer the existing syntax. I do like how your proposed syntax makes the parentheses unnecessary.