Reason: [feature] arg-less switch

[bobzhang]

switch {
 a > b => ..
 c  => ...
}

which is equivalent to

switch () {
() when a >b => ..
() when c => ..
}

[bassjacob]

what would be the reason to use this over if/else?

[chenglou]

That's kinda neat. Pushing people toward switch is nice. Though it seems to trigger Warning 25: bad style, all clauses in this pattern-matching are guarded which we don't suppress

[bobzhang]

You can do a syntax check that argless switch requires a default branch

[OvermindDL1]

In the erlang ecosystem this construct is known as cond, if you want a different name for it (although switch seems fine for it too if no ambiguities pop up).

[hcarty]

Could the syntax be something different to help avoid visual ambiguity and to emphasize that a catch-all case is not something to encourage in normal switch expr { | case => ... }uses?

Maybe:

switch if {
| a > b => ...
| c < d => ...
| else => ... /* "else" is a keyword so maybe safe to use here? */
}

It could desugar to if/elses or switch with a catch-all case replacing the else case.

[bsansouci]

Is if/else not good enough?

switch {
 a > b => ..
 c  => ...
}

vs

if (a > b) {
   ...
} else if (c) {
   ...
}

?

[chenglou]

switch { and switch () { won't be possible in master since it conflicts, I think. But this might work:

if {
| a > b => ..
| c  => ...
}

Or drop the brackets:

if
| a > b => ..
| c  => ...

[anmonteiro]

I actually would much prefer if this were in if rather than switch, so personally I think it's a good thing that it conflicts :)