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

30 Mar 2010


      On Mon, 2010-03-22 at 14:30 +0100, Hans Aberg wrote:
...
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.
Another option which might be interesting is s7 (by Bill Schottstaedt),
available here:

  https://ccrma.stanford.edu/software/snd/

"It exists as just two files, s7.c and s7.h, that want only to disappear
into someone else's source tree"

More details in the "manual" link in that page. 
-- Fernando
...
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

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

Fernando Lopez-Lezcano