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1 point by shader 3431 days ago | link | parent

currently fns takes an optional filter argument, and defaults to prefix. i.e., you give it a string, and it keeps all of the keys from the "sig" table that begin with that string. So it finds both macs and defs.

I've modified my version so that a) if you don't give any arg it returns the signatures all currently defined functions and macros, and b) it can take unquoted symbols as input instead of just strings. That makes use from repl easier.

I don't know how I would filter defs from macs. Maybe have def and mac store them in a different table? How do you get the object associated with a symbol? If I knew that, we could filter based on (type key).

2 points by cchooper 3431 days ago | link

  (eval symbol)


1 point by shader 3431 days ago | link

That works, I suppose


1 point by cchooper 3430 days ago | link

I'm afraid it's the only thing that works.

But there's nothing wrong with it. You're doing non-performance sensitive metaprogramming, which is a perfect example of where eval should be used.


1 point by shader 3430 days ago | link

I just found the macro varif on Anarki, which returns the value if bound. Would that be better, or worse? I should think it might be a little better, but I don't know.

True, this is running, I think, in the repl. So I don't think it matters that much. But having a good way to look up the value of a symbol is kind of important, I think. I want to do similar things that might be used in a "performance-sensitive" environment, not that arc is really performance sensitive in general. ;)


1 point by cchooper 3427 days ago | link

varif will be better if you can use it in what you're doing. It doesn't evaluate its argument, which might make it useless to you.


1 point by shader 3427 days ago | link

rntz wanted two separate functions to search macs and defs, so I suggested filtering the sig table based on whether each symbol was a mac or fn; that would only be possible if there was a way to turn the symbol into a value we could take the type of.


1 point by cchooper 3426 days ago | link

But do you need to evaluate the argument to varif in your implementation? If so, then it's no good to you.