Conditional echos

[ollien]

Right now, it's a bit clunky in the language to write conditional echos. I've often found myself resorting to this

case condition {
  True -> echo wibble as "wibble"
   False -> wobble
}

Others in the Discord have suggested making use of bool.guard, but it's a bit unintuitive because that requires negating the condition

bool.guard(
  !condition, !condition, fn () { echo wibble as "wibble" }
)

It would be great if this could be part of the echo syntax. Something like

echo wibble if condition as "wibble"

[lpil]

We intend to not add additional flow control features to Gleam, and any new feature to the core language have to be in aid of a large problem in Gleam programming, but this seems very niche and largely about stylistic preference.

[ollien]

Yeah understandable. It is a common technique I find a bit clunky, but I understand your hesitation.

[inoas]

@ollien

Others in the Discord have suggested making use of bool.guard, but it's a bit unintuitive because that requires negating the condition

given has given.not but it is always lazy by design, which may not what you want here.
You could implement a bool.guard_unless or similar in userland?
Or an effect_if and effect_unless? All similar to bool.guard?

This also came to my mind:

fn echo_unless(cond, val) {
  case cond {
    True -> echo val
    False -> val
  }
}

However the line numbers will be off for this one.

Would a trace similar to an echo be possible AND useful?