A big let and with change

[algernon]

This drops the outer brackets from let and with, but does NOT change let behaviour anymore. That'll be another change, if at all.

See #713 and #852.

(Thanks for the reviews so far, the scope of this change was drastically reduced.)

[farhaven]

LGTM, I like it.

[gilch]

👎 I approve of removing the extra [] from let, but not of making it a mere alias for setv, which is counter to #240. The body has no special meaning, which is still confusing. let is marginally more useful as it is now, despite its problems.

As for with, can we use nil/None as a dummy variable, as discussed in #852? I haven't tested it, but from looking at the code, it doesn't appear to work.

[algernon]

(with [nil (open "touch-me-gently" "w")] (print "!")) works. It worked before too, just as _ too, (with) didn't change in that regard.

I'll redo this PR, and instead of completely changing let, I'll just drop the brackets, and deal with let elsewhere.

[algernon]

Updated, now it doesn't change let all that much, just drops the brackets.

[gilch]

What happens if with's [] has an odd number of arguments? Can you add an error check?

[algernon]

The old version and the new both do the same thing: hope it does something sane-ish. I'll add a test case, though.

[algernon]

Actually, there already is such a test:

https://github.com/algernon/hy/blob/3e7453e5171c82be3c6d15660600ac6d905f3f83/tests/native_tests/language.hy#L574

[zackmdavis]

(A thought prompted by #907—) as long as we're breaking the world in order to favor Clojure-style brace-minimizing implicit pairings, we should probably do cond as well.

[algernon]

I don't think it's worth removing brackets from cond: we just recently made it so that the vectors have an implicit do, so you can have multiple statements.

Thus:

(cond
 [(= foo bar) (do-this) (do-that)]
 [(= hue hue) (do-something-else) (do-that-too)])

If we drop the brackets, we lose the ability to do an implicit do. I believe the implicit do is much more useful than dropping the brackets would be.

[gilch]

We could support both with a variadic if, see #830.

[algernon]

Ping @hylang/core.