On 8/18/05, Kevin Smith kevin@electricanvil.com wrote:
(define-macro (print-line msg) (list `(display ,msg) `(newline)))
When I try to use the macro from the repl I get the error message:
(print-line "hi") hi ***ERROR in (console)@38.1 -- Operator is not a PROCEDURE
Consider the expansion of the macro: (print-line "hi") -> ((display "hi") (newline))
Therefore (display "hi") is evaluated (causing the side-effect of printing "hi") and then we have: (<result of display> (newline))
Now I believe that (newline) will be evaluated giving: (<result of display> <result of void>)
and gambit complains that <result of display> isn't a function which can be called. Which is fair enough since it's the value #!void (aka NULL).
If I were writing that macro I would do something like: (define-macro (print-line msg) `(begin (display ,msg) (newline))
Hope that helps.
AGL