3 ms·

Yes - everything will act as if that stack frame was heap-allocated and still exists* . You can modify the value(s), define multiple functions sharing the same

Yes - everything will act as if that stack frame was heap-allocated and still exists* . You can modify the value(s), define multiple functions sharing the same variable bindings, etc. A lot of common language features (such as conventional objects) can be implemented as syntactic sugar on top of closures. (Same with continuations.) * Compilers/interpreters are free to do optimizations that won't affect results, like only heap-allocating the closures that escape their scope.

jacquesm 16y ago
Thanks!
- silentbicycle 16y ago
  When I'm struggling with what a programming concept means, I find it helpful to try implementing it in a toy interpreter. Efficiency is irrelevant, it just needs to model the concept correctly. Many concepts really aren't that complicated if you're not worried about optimization, and getting to a working model tends to shake out the aspects you don't completely understand. (This is also why books have exercises.)
  - jacquesm 16y ago
    > When I'm struggling with what a programming concept means, I find it helpful to try implementing it in a toy interpreter. That's my 'I have understood' benchmark. If I can re-implement something without any reference to outside sources. My goal is to write a little lisp or scheme from the ground up from nothing but the lambda calculus and some bits & pieces. It'll be slow as molasses but it will help me to really grok it. That's why I've been reading up on all this stuff over the past year or so. After that I think I'm ready for something more involved, like clojure. I realize that this is not a very efficient way of learning but in the long run it tends to pay off. Knowing what goes on under the hood is an advantage.
    - silentbicycle 16y ago
      Yeah, it seems like the long way around, but it really adds up over the years! You'll probably want to get Quinniec's _Lisp in Small Pieces_, if you don't have it already. It covers several aspects of implementing Lisp interpreters and compilers, the lambda calculus, a bit on semantics, etc. (It mostly focuses on Scheme.)

jacquesm 16y ago

Thanks!

silentbicycle 16y ago
When I'm struggling with what a programming concept means, I find it helpful to try implementing it in a toy interpreter. Efficiency is irrelevant, it just needs to model the concept correctly. Many concepts really aren't that complicated if you're not worried about optimization, and getting to a working model tends to shake out the aspects you don't completely understand. (This is also why books have exercises.)
- jacquesm 16y ago
  > When I'm struggling with what a programming concept means, I find it helpful to try implementing it in a toy interpreter. That's my 'I have understood' benchmark. If I can re-implement something without any reference to outside sources. My goal is to write a little lisp or scheme from the ground up from nothing but the lambda calculus and some bits & pieces. It'll be slow as molasses but it will help me to really grok it. That's why I've been reading up on all this stuff over the past year or so. After that I think I'm ready for something more involved, like clojure. I realize that this is not a very efficient way of learning but in the long run it tends to pay off. Knowing what goes on under the hood is an advantage.
  - silentbicycle 16y ago
    Yeah, it seems like the long way around, but it really adds up over the years! You'll probably want to get Quinniec's _Lisp in Small Pieces_, if you don't have it already. It covers several aspects of implementing Lisp interpreters and compilers, the lambda calculus, a bit on semantics, etc. (It mostly focuses on Scheme.)