On 24.07.2024 03:06, spacecadet wrote:
> Hi, I didn't see a help-guile list, I hope this isn't out of place
I think the guile-user list might be more appropriate.
> I'm trying to lexically bind a macro to a lexically bound transformer
> procedure
>
> (let ((outer (lambda (x) #''())))
> (let-syntax ((inner outer))
> inner))
>
> This is producing an error
> "reference to identifier outside its scope in form outer"
>
> My goal is to load external macros without any top-level definitions
> I don't know if the way the macro expander works will allow this
> Any help appreciated, thanks!
Scheme evaluation could be considered to happen in two parts, regardless of
whether the implementation actually has a compiler:
1. The compile-time execution of code
2. The run-time execution of code
(Guile actually has a compiler so it's definitely like this in practice too.)
The 'let' form works in the context of run-time execution, whereas 'let-syntax'
works in compile-time execution. Although compile-time code can "see" that a
variable called 'outer' is bound in the lexical scope, the actual value of the
binding will only exist at run-time, so you can't rely on it during
compile-time execution.
The following works:
(let-syntax ((outer (lambda (x) #'(+ 1 2))))
(let-syntax ((inner (lambda (x) (outer x))))
(inner)))
The 'inner' has to be a lambda too, and can't be bound to 'outer' directly. I'm
not sure why.
--
Taylan
