If · ideas · Zulip Chat Archive

Stream: ideas

Topic: If

7rans (Dec 23 2023 at 09:55):

First let me say that Roc might be the nicest functional languages Ive come across.

One thing that always irks me though is how if statements seem like they are always ripped right from the imperative world — clunky keywords with blocked statements.

How to fix? On the face of it, if is a function that takes three arguments— a boolean and two lambdas. So we might write something like:

ifElse (foo) (\{} -> doThus) (\{} -> doElse)

Forgive me if this isn’t quite the right syntax. I am new to Roc, but I think the idea is clear.

However, this isn’t the nicest looking b/c of parens and empty args. Some sugar would be nice.

It occurs to me that it should be possible to unify if and when into a single construct.

foo if
  Bool.true -> doThus
  Bool.false -> doElse

With a special character for Bool.true, say | (pick whatever you prefer) then

foo if
  | -> doThus
  _ -> doElse

when would be the same just different pattern matches.

bar if
  Ok v -> …
  Err e -> …

Seems very elegant to me. Thoughts?

Anton (Dec 23 2023 at 10:43):

Last updated: Jun 16 2026 at 16:19 UTC