3 ms·

Static analysis is already being done, since it is being compiled. Supercompilation taken to the extreme is very slow, but don't take it to the extreme, doing j

by seles 15y ago

Static analysis is already being done, since it is being compiled. Supercompilation taken to the extreme is very slow, but don't take it to the extreme, doing just enough to evaluate the expressions which are passed into eval would be fine (and these are often simple, macro like substitutions).

takeoutweight 15y ago
I'm not sure if we share the same notion of supercompilation. The whole point of supercompilation is to speculatively evaluate terms to supply branch-level constraints that propagate through the call graph, enabling program transformations such as inlining, dead code elimination, partial evaluation and deforestation. Whole-program transformations such as these are done during compilation (i.e. in the dev environment and not in production.) How would you retro-actively undo an existing transformed piece of code when a new form is observed by eval? How would you maintain a list of already-applied transformations to allow new code to be specialized? Supercompilation is not an incremental procedure.
- seles 15y ago
  My notion of supercompilation is just the evaluating of expressions at compile time that do not depend on things at run time. A trivial case that most compilers do is converting print 1+1 to print 2. Since 1+1 does not depend on anything that could happen at run time and does not produce any other side effects. (You need to analyze that + hasn't been overloaded to have side effects/etc.). The idea is that many of the expressions being passed into eval could be calculated in entirety at compile time, so there is no need to have eval in the compiled result at all. Just evaluate at compile time, remove the eval and the quotes. I am not talking about trying to optimize eval, if you have a variable string going in, you can't possibly do that. I guess I shouldn't have used the term supercompiling, it may mean something more powerful than in the cases I'd seen it and I was probably trying too hard to use a buzzword...
  - takeoutweight 15y ago
    The term that describes what you are referring to is 'partial evaluation'

by seles 15y ago

takeoutweight 15y ago

I'm not sure if we share the same notion of supercompilation. The whole point of supercompilation is to speculatively evaluate terms to supply branch-level constraints that propagate through the call graph, enabling program transformations such as inlining, dead code elimination, partial evaluation and deforestation. Whole-program transformations such as these are done during compilation (i.e. in the dev environment and not in production.) How would you retro-actively undo an existing transformed piece of code when a new form is observed by eval? How would you maintain a list of already-applied transformations to allow new code to be specialized? Supercompilation is not an incremental procedure.

seles 15y ago
My notion of supercompilation is just the evaluating of expressions at compile time that do not depend on things at run time. A trivial case that most compilers do is converting print 1+1 to print 2. Since 1+1 does not depend on anything that could happen at run time and does not produce any other side effects. (You need to analyze that + hasn't been overloaded to have side effects/etc.). The idea is that many of the expressions being passed into eval could be calculated in entirety at compile time, so there is no need to have eval in the compiled result at all. Just evaluate at compile time, remove the eval and the quotes. I am not talking about trying to optimize eval, if you have a variable string going in, you can't possibly do that. I guess I shouldn't have used the term supercompiling, it may mean something more powerful than in the cases I'd seen it and I was probably trying too hard to use a buzzword...
- takeoutweight 15y ago
  The term that describes what you are referring to is 'partial evaluation'