if's else-clause should be optional

[vinipsmaker]

I see the flavor of the language being very expression-oriented, but Rhombus already detects a lot of errors at parse time (even more if you use Rhombus-static) so having an implicit else-clause that returns #void when nothing is needed might not be harmful.

I see myself writing lots of debugging code like the following one in these early stages while I'm learning the language:

if rbp == 0:
| println("surprise surprise " ++ String.from_int(token.lbp))
| []

The else-clause here adds no value.

Btw, good job on the guard design. I almost gave up on the language when I saw that the expression-oriented nature + the lack of a return statement, but guards allow one to avoid Hadouken indentation by retaining the "return early" (in a way). It retains the cleanness of the return early idiom in an expression-oriented language.

[LiberalArtist]

Rhombus provides when and unless forms to use instead of a one-armed if variant to more clearly communicate your intent. Your example becomes:

when rbp == 0:
| println("surprise surprise " ++ String.from_int(token.lbp))

I haven't been involved in any Rhombus design discussions on this point, but I expect it was a deliberate choice based on experience to make if require an “else” clause. The RnRS Scheme reports allow for one-armed if, as does the Racket community's #lang mzscheme, but the #lang scheme language made the “else” clause mandatory, even before #lang racket. (Actually, I had thought R6RS had also required an “else,” but apparently I misremembered.) Moving the one-armed functionality to dedicated when and unless forms makes your intent clear to future readers, besides preventing some annoying and easy-to-overlook bugs.

I can only speak for myself, but I'd be surprised people want to return to the days of (if #f #f) (the cryptic portable Scheme way of getting the implementation's equivalent to what Rhombus calls #void).

[vinipsmaker]

Rhombus provides when and unless forms to use instead of a one-armed if variant to more clearly communicate your intent.

There's no need for an one-armed if then. Thank you.