> No support for first class continuations
I'm not sure about how people would feel about this. I have mixed feelings. It feels like a loss of many things. What are the gains from ditching continuations?
I'm not sure about how people would feel about this. I have mixed feelings. It feels like a loss of many things. What are the gains from ditching continuations?
> What is needed is a small, portable compiler that generates more or less "natural" C code with minimal dependencies and runtime system that supports at least the basic constructs of the language and that puts an emphasis on producing efficient code, even if some of the more powerful features of Scheme are not available.
Since C doesn't support continuations, it is not possible to have continuations and at the same time generate "natural" C code.
Consider how you would implement first class continuations. It's not possible to do CPS transformation (given the goal of natural code generation) - since that's a whole program transformation.
Since CHICKEN actually does this, I'll add the proviso of "without a GC or costly runtime".
Regardless of what we call the style, it isn't simple any more.
For people interested in the internals of Chicken Scheme (I suspect sctb already knows):
Plus honestly most of the uses of continuations that would make sense in the sort of relatively low level code this is aimed at can be built out of a few special purpose macros (and possibly a small amount of crying) - scheme code tends to lean on first class continuations for a lot of things that don't really need them, Because It Can.
e.g. Paul Graham's On Lisp shows how to build (a subset of) continuations out of macros, and getting something like clojure's 'recur' out of that would probably give you simpler macros than pg's code uses.