In this neighborhood

scala> try ??? catch case t => 42
val res0: Int = 42

scala> 27 match case t => 42
-- [E040] Syntax Error: ------------------------------------------------------------------------------------------------
1 |27 match case t => 42
  |         ^^^^
  |         '{' expected, but 'case' found

I'd be happy to contribute this but I have no idea where to start. Can someone hint at where to look to implement such change?

"Parens vs braces" is the new "tabs vs spaces".

I expressed hope that the new SIP to allow parens around cases will also cover the "one-liner" examples.

The motivation is that if it allows the one-liner

xs.map(case t: T => f(t))

then it's also reasonable to accept

xs.map: case t: T => f(t)

and then when it's not a one-liner but still a single case

xs.map: case t: T =>
  val v = f(t)
  v

which is further motivated by manual parameter untupling

pairs.map: case (x, y) =>
  body

Note that it does not yet accept one-liners after colon:

xs.map: x => x + 1

The previous judgment was that braceless colon is not intended to eliminate parens; but maybe that will change with the new front in the war between braces and parens. That is, all the options for bracketing code get taken to their logical conclusion in the brackocalypse. Abrackalypse?

https://contributors.scala-lang.org/t/sip-xx-allow-partial-function-literals-to-be-defined-with-parentheses/7207/12?u=som-snytt