Rationale behind : for labeled arguments

[wilkomanger]

Hi, I was wondering what the rationale behind using : for labeled arguments is, such as:

let x = some_function(label_a: 30, label_b: 40)

From what I can tell, Gleam uses : as a type bound 'operator' (except for function return types), which doesn't really match the use of the argument labels.

It would seem more consistent to use =, as with let bindings, since in the end you're also assigning a value to a name with labeled arguments. It would look like this:

let x = some_function(label_a = 30, label_b = 40)

I'm curious what the thought process behind this was!

[lpil]

It's a mix of being similar to mainstream languages that use :, and to avoid confusion with related languages like Erlang or Elixir where this

let x = some_function(label_a = 30, label_b = 40)

is semantically the same as this

let label_a = 30
let label_b = 40
let x = some_function(label_a = 30, label_b = 40)

Overall there's not much in it. Perhaps if we had thought : as an operator for annotating a type we wouldn't have used it for labels also.

[wilkomanger]

I see 👍 Too late to change now I suppose? 😄

[lpil]

Yup, way too late!