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3 points by greatness 6117 days ago | link | parent

The odd thing about this is that I KNOW it should break, but I can't make it do so.

  arc> (let oaf 1 (when 2 3))
  3
I'm pretty sure it is because it evaluates the macro expansion ahead of time.

  arc> (macex '(when 2 3))
  (if 2 (do 3))
Additionally, does anyone know why if isn't considered an object:

  arc> if
  Error: "reference to undefined identifier: _if"


3 points by randallsquared 6117 days ago | link

The symbol 'if is a special operator, not a macro or function. The special operators in Arc's compiler are quote, quasiquote, if, fn, and set.

Probably it would be convenient to have an object tagged as a special operator for those, but it would be documentation, not functional code.

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4 points by pg 6117 days ago | link

Special operator is what they're called in CL. I don't know offhand what they're called in Scheme. But what it amounts to is that if only exists as a clause in the compiler.

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2 points by randallsquared 6117 days ago | link

"Special operator is what they're called in CL."

Yeah, I know much less about Scheme than CL, so I used the CL term.

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1 point by jimbokun 6114 days ago | link

What are they called in Arc? :)

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2 points by pg 6114 days ago | link

Special operator sounds good. Or axiom, if we want to be fancy.

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1 point by vsingh 6117 days ago | link

Hmm.

I guess the macros in the form are expanded with reference to the context of the entire form (the global context).

Does this mean we don't have macrolet?

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1 point by simonb 6117 days ago | link

It probably has more to do with if being one of the primitives (or axioms if you will).

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