Qualified import

[lpil]

Hello!

I prefer to qualify my imported functions by default as I believe that the module name on the call makes it much clearer where functions are defined. Is there a way to import functions in a qualified way? It seems that import module.function permits both qualified and unqualified calls of the imported function.

Cheers,
Louis

[j14159]

Given:

mod a
export add
let add x y = x + y

Then this is OK:

mod b
import a.add
let foo () =
  -- both of these will work:
  let _ = a.add 1 1 in
  let _ = add 1 1 in
  :done

And this is OK:

mod b

let foo () =
  -- qualified only since there's no import:
  let _ = a.add 1 1 in
  :done

But this will fail to compile:

mod b

let foo () =
  -- works:
  let _ = a.add 1 1 in
  -- should fail because no import:
  let _ = add 1 1 in
  :done

Importing only works for exported functions and is a way to drop qualification, it won't expose an un-exported function from, for example, a. Does this run counter to what you're after?

[lpil]

Oops! Too much Haskell and Elm. I presumed some sort of import statement is always required. Thanks!

[lpil]

Is it possible to alias a long module name? Something like alias my_app_data_user as user ?

[j14159]

Not at present, no. I'm totally fine with seeing that feature added though it'd be low priority for my own personal work queue. Probably not a huge change, can probably accomplish this with a rewrite in alpaca_ast_gen.erl.

[OvermindDL1]

Is it possible to alias a long module name? Something like alias my_app_data_user as user?

OCaml's syntax for that would be much nicer:

module User = My_app_data

[lpil]

I didn't want to imply this would go as far as a first module system :)

[OvermindDL1]

I didn't want to imply this would go as far as a first module system :)

Aww, but the beam VM would so very well support first-class modules. ^.^

[j14159]

Aww, but the beam VM would so very well support first-class modules. ^.^

I'm working on a reading list for this :) (mostly because I have a lot to learn)

[OvermindDL1]

I'm working on a reading list for this :) (mostly because I have a lot to learn)

Oh if you have questions about first class modules, higher polymorphic modules, Functors, or basically anything else in OCaml, I can explain in detail. :-)

HPT's (like OCaml's Module system) is significantly more powerful than essentially all of Haskell's typing system alone as it can emulate, for example, even typeclasses (as a VERY simple example) but significantly more performant in compilation time (and with no runtime costs over standard dispatch, which even that is optimizable out with a couple simple passes). All while HPT's have a singular syntax representation unlike Haskell's type system horrors. :-)

[j14159]

I can explain in detail. :-)

I may yet take you up on that :) Currently I'm still intrigued by the possibilities in 1ML but need to dig in more. I'm thinking we do need something that synthesizes Erlang modules out of Alpaca sig+module combinations, it's just not at the very top of my list yet :D (algebraic effects and the FFI are other large-scale/scope things to figure out too, along the lines of discussion in #7).