Optional Arguments with Defaults for Gleam

Notice

One can be doing quite a bunch of things wrong and get runtime errors.

This library is more a cursed hack than a good solution and should be mostly used to explore how a gleam library public API would look like if gleam ever supported optional arguments with defaults out of the box.

Installation

gleam add opt_args_with_defs_for_gleam

Example

import gleam/io
import opt_args_with_defs_for_gleam.{O, OB, OF, OI, ON, OS, get_arg, get_args_with}

// Can use string keys as well, but that is more error prone.
type OptionalArgumentKeys {
  SomeNumber
  SomeFlag
}

fn fun_with_typed_keys(options: options_keyword_list) -> #(Float, Bool) {
  let args =
    [#(SomeNumber, OF(1.0)), #(SomeFlag, OB(True))]
    |> get_args_with(options)

  let assert OF(some_number) = get_arg(args, SomeNumber)
  let assert OB(some_flag) = get_arg(args, SomeFlag)

  #(some_number, some_flag)
}

pub fn main() {
  fun_with_typed_keys([#(SomeNumber, OF(2.0))])
  |> io.debug() // #(2.0, True)
}

Further documentation can be found at https://hexdocs.pm/opt_args_with_defs_for_gleam.

Development

gleam test  # Run the tests