How to pass MAKE variables to guile

I'm using GNU Make with Guile. How do I pass Make variables to Guile?

%.txt:
    @echo $* $(guile (string-upcase $*))

What I want to see is this:

$ make foo.txt
foo FOO

What I get is an error, Unbound variable: foo. My Guile invocation expands to (string-upcase foo), and foo is unbound. I can put quotes around the variable and then I get the result I'm looking for:

$(guile (string-upcase "$*"))

This feels wrong. What if the string contains double quotes? It feels like there would be a more formal mechanism for passing values into Guile.

https://www.gnu.org/software/make/manual/html_node/Guile-Types.html goes into some detail about passing values from Guile to to Make, but I can't immediately see anything about passing them in.

Solution

You can use gmk-expand to expand $* more safely, like this:

%.txt:
        @echo $* $(guile (string-upcase (gmk-expand "$$*")))

Or you can use the following technique to bind unary functions so that they can be invoked with $(call):

define _init :=
    (define (gmk-bind1 proc)
        (let ((name (symbol->string (procedure-name proc))))
             (gmk-eval (string-append
                        name "=$$(guile ("
                        name " (gmk-expand \"$$$$1\")))"))))
    (gmk-bind1 string-upcase)
endef
$(guile $(_init))

%.txt:
        echo $* $(call string-upcase,$*)