feat(askscript): function type constructor

[mhagmajer]

fun(returnType, arg1Type, arg2Type, ..., argNType)

Last argument can be rest in this case last argument is true:

fun(string, array(number), true) - same as (s: string, ...numbers: number[]) in TypeScript

Examples

const myToString: fun(string, int) = fun(n:int): string {
  n:toString
}

• update documentation

[czerwinskilukasz1]

This PR changes function type used in .ask files to a new syntax.
I think the new syntax is confusing, e.g. fun(int, int, int) doesn't look like the a 2-argument function.
Let's chat about this change.

[czerwinskilukasz1]

Also, this PR goes beyond the priorities from our Roadmap.
Let's focus on our current priorities before we discuss this syntax change.

[mhagmajer]

This PR changes function type used in .ask files to a new syntax.
I think the new syntax is confusing, e.g. fun(int, int, int) doesn't look like the a 2-argument function.
Let's chat about this change.

@czerwinskilukasz1 I'm all for creating some syntax sugar to make it easier to use, see #49

[czerwinskilukasz1]

@mhagmajer , is this PR ready for review? I'd say no, because it links issue #49 , which is about a syntax sugar (int, int) -> int, but there is not such syntax introduced in your change. Instead you use the confusing fun(int, int, int).
I'd convert it to a draft. Thoughts?

[mhagmajer]

@czerwinskilukasz1 this is not the recommended syntax for function type. This is an implementation detail - all types need constructors which are function that result in the given type. Function is a type of value so we need a function constructor for it. We can then have additional syntax sugar for it.

Because types are not checked by runtime yet, I created this PR only for the tests to showcase the basic syntax for creating function types.

Examples of function constructors:

const a: int({ positive: true }) = 5

const b: fun(int, int) = fun (a: int): int { 5 }

// possible syntax sugar:
const c: (int) -> int = fun (a: int): int { 5 }

[czerwinskilukasz1]

Because types are not checked by runtime yet, I created this PR only for the tests to showcase the basic syntax for creating function types.

Examples of function constructors:

const a: int({ positive: true }) = 5

const b: fun(int, int) = fun (a: int): int { 5 }

// possible syntax sugar:
const c: (int) -> int = fun (a: int): int { 5 }

The ticket description as well as your description in this PR and our discussion in this PR were about a different feature than you mentioned today.

[mhagmajer]

@czerwinskilukasz1 can you explain please? I meant this PR to introduce the generic function type constructor

[czerwinskilukasz1]

@czerwinskilukasz1 can you explain please? I meant this PR to introduce the generic function type constructor

Of course. The linked issue is about (int, int) -> int syntax:

[czerwinskilukasz1]

Last argument can be rest in this case last argument is true:

fun(string, array(number), true) - same as (s: string, ...numbers: number[]) in TypeScript

I find fun(string, array(number), true) syntax complex and confusing. How about we add ... to AskScript too?

[mhagmajer]

@czerwinskilukasz1 all syntax sugars are useful to make writing code easier :)