Arc Forumnew | comments | leaders | submitlogin
1 point by cchooper 5822 days ago | link | parent

To clarify those points:

They're not recursive in the same way functions are:

  (mac foo (x)
    (if x '( ...)
        (foo ...)))
> Even using macros and some non-turing-complete subset

But macros on their own aren't. By comparison, Pure can do everything with rules.



6 points by rntz 5821 days ago | link

Actually, I apologize. My earlier statement about macros plus some turing-incomplete subset of arc being turing-complete makes no sense. There is no such thing as "macros on their own". Macros are just Arc code that gets evaluated before what we like to think of as "runtime". Arc macros sans the rest of arc are nothing. The "difference" here is not that macros are (or rather, macroexpansion is) turing-incomplete. The difference is that Arc delineates macroexpansion from normal evaluation, whereas Pure doesn't have a distinction; everything is term rewriting.

-----

1 point by cchooper 5821 days ago | link

On the other hand, it's debatable whether being non-recursive in this way is a difference from Pure.

-----