Arc Forum | See, I told you you'd convince me to come around to your way of thinking, once I...

Arc Forum

1 point by shader 5939 days ago | link | parent

See, I told you you'd convince me to come around to your way of thinking, once I'd asked enough questions to find out the reasons for the choices you've made.

So, how hard is it to take what you've made so far, and generalize it to work with any kind of environment, and not just packages? So, things like destructuring functions, naming environments, passing them around, etc. Would this allow us to avoid shadowing variables by naming which level they came from explicitly?

Also, if I type in the symbol '<arc>bar, will the contexter read that and presume I'm looking for the bar in arc, or will it rename it <foo><arc>bar? And which is better?

If it's the latter, how would you propose we directly reference a particular environment? Would that be pack.sym, like I had thought earlier?

1 point by almkglor 5939 days ago | link

> So, how hard is it to take what you've made so far, and generalize it to work with any kind of environment, and not just packages?

Hmm. Well, if you want to be technical about things, one Neat Thing (TM) that most compilers of lexical-scope languages (like Scheme and much of CL, as well as Arc) do is "local renaming". Basically, suppose you have the following code:

  (fn (x)
    (let x (+ x 1)
      x))

This is transformed (say by arc2c) into:

  (fn (x@1)
    (let x@2 (+ x@1 1)
      x@2))

Note that the renaming could actually be made more decent, i.e. something readable. For example, in theory the renaming could be done more like:

  (fn (<fn>x)
    (let <fn/let>x (+ <fn>x 1)
      <fn/let>x))

In fact I am reasonably sure that Scheme's hygienic macros work after local renaming, unlike CL's which work before renaming. You'll probably have to refer to some rather turgid papers though IMO, and decompressing turgid papers is always hard ^^.

> Also, if I type in the symbol '<arc>bar, will the contexter read that and presume I'm looking for the bar in arc, or will it rename it <foo><arc>bar? And which is better?

Well, since packages are constrained to be nonhierarchical, <arc>bar is considered already packaged and the contexter will ignore them. The contexter will add context only to unpackaged symbols.

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