Re: [chuck-users] Guile C++ wrap

On 22 Mar 2010, at 14:01, Kassen wrote:

Isn't Guile a Scheme dialect/implementation?

Yes, it is a C-library version. It turns out that it has the lambda symbol available in a header . So it is possible to use it to build lambda expressions form scratch, which is otherwise not possible in Scheme. There are some problems here: a compiled lambda expression becomes proceudre, which cannot be treated as an expression anymore. For example if I define expression e1 = y >> x + y; and compiles it into a procedure f, then if I write expression e2 = x >> f; and then compile it into g, the symbol "x" in f will be unbound and always produce an unbound variable error.

I'm starting to really like some of Scheme's tricks.

So it is good for playing around with too see what might be required, but is not suitable as a library.

I thought about writing some utility functions for ChucK inspired by it, like the anonymous -in line- "if". I really like that one. Sadly that won't currently fly in any sensible way due to the type-system, while we could actually make sure during parsing/compilation that this particular "if" will return values of the appropriate type and wouldn't need to wait for runtime muck-ups.

Mind you, I'm not sure this sort of stunt would be a good idea at all, but I could see how it would at least be possible.

Yes, that is not only possible but important to have. I have started to work with the "case" function; its symbol is also in the header: If one uses a Haskell style definition with conditions function1 f; f(x) | x < 0 = -1; f(x) | x == 0 = 0; f(x) | x > 0 = 1; then that is in Haskell translated into f = x >>= case x of (x < 0) -> -1 (x == 0) -> 0 (x > 0) -> 1 In other words, by making those conditional formulas available as objects, one can reduce such function definitions to just the lambda.

We should be careful about chucking out the baby because we want to add new bathwater.

So that is not necessary. Hans