potential package: assert

[aslilac]

Implementation would probably be mostly two functions

assert_or_die

pub fn assert_or_die(val: Bool) {
  case val {
    True -> val
    False -> panic
  }
}

Use case

pub fn process_data(important_data: Data) {
  assert_or_die(isValidSignature(important_data.signature))
  // do things with data
}

This is useful, especially for hacking things out quickly, but isn't very idiomatic, hence the need for our second implementation.

assert_or_error

pub fn assert_or_error(val: Bool, error: e, func: fn() -> a) -> Result(a, e) {
  case val {
    True -> Ok(func())
    False -> Error(error)
  }
}

Use case

pub type DataProcessingError {
  InvalidSignature
}

pub fn process_data(important_data: Data) -> Result(a, DataProcessingError) {
  use <- assert_or_error(isValidSignature(important_data.signature), InvalidSignature)
  // do things with data
}

This still allows us to make assumptions in our code, but allows us to propagate errors instead of killing the program outright.