Support for something like Rust if-let

[tknawara]

Hi team,

I'm very new here, so apologies if I didn't provide enough details. I'm wondering if you have given any thoughts around supporting something like rust if let

The basic idea is to allow for destructuring in if condition and bind everything in the if scope, you can already do that with match of course, but I often find myself only interested in a single case of an enum for example while the remaining cases won't need special handling for them.

This is already supported in different scala constructs like for comprehensions and would be nice to do something like

if Some(v) = myOption then
   ...

instead of

if myOption.isDefined then
  val Some(v) = myOption
  ....

It gets complicated if you want to use v further in the condition though

if Some(v) = myOption && v.xyz then
  ...

[He-Pin]

This reminds me dart-lang/language#4205

[tknawara]

Similar discussion happened in F# fsharp/fslang-suggestions#705

[xiaoshihou514]

Maybe use the function .collect?

[joan38]

What's the benefit over:

myOption match
  case Some(v) if v.xyz =>
    ...
  case None =>

?
More compact?

[kyouko-taiga]

There's been a (pre-)pre-SIP on this topic with a lengthy explanations of the motivations for such a feature: https://contributors.scala-lang.org/t/pre-sip-s-improving-the-expressiveness-of-conditional-control-flow/6488

There are plans to work on a proper SIP in the near future. Any help is welcome obviously.