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Scriptor / pharen

Lisp to PHP Compiler
http://pharen.org
BSD 3-Clause "New" or "Revised" License
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Bad OR behaviours #21

Closed domdefelice closed 13 years ago

domdefelice commented 13 years ago

(or FALSE "string") should return "string" but returns 1. It always returns 0 or 1, but should return 0 (FALSE) or the element that was not FALSE, so to make possible to use something like (print (or variable "default string")).

jeromebaum commented 13 years ago

Another case where we should be following traditional lisp semantics. Just in case: The same goes for IF, AND, COND, etc. so if we have those and they don't already to this, make sure they do (though I believe IF already follows this).

Also, check out this xkcd for some real insight: http://m.xkcd.com/870/.

Scriptor commented 13 years ago

The issue here is that PHP doesn't seem to natively support this behavior for its logical operators. I guess the solution would be to convert them to ternary statements but I'm not sure if there'd be a performance penalty. Ideally there shouldn't be, but the PHP internals can be rather messy.

jeromebaum commented 13 years ago

Doesn't the IF implementation just assign a variable? Either way, modulo multiple evaluation (which would be solved with a LET), just translate:

(or a b)

to:

(if a a b)

Scriptor commented 13 years ago

Yep, I just wasn't sure if PHP would add some extra overhead to if statements. Some quick benchmarks show that if statements were as fast as ternary statements. I really need to stop irrationally fearing PHP internals :)

Implementing this now.