I am playing with the $(guile ...) support in GNU Make, but I'm having trouble generating a complete recipe from within Guile.
This traditional approach works as expected:
brazil:
<--tab-->@echo Ere I am J.H.
(where <--tab--> is an ASCII tab character, as required)
But when I try this supposed-equivalent:
$(guile (format #f "brazil:~%~/@echo Ere I am J.H."))
I am treated to the following error message when I run make brazil:
make: *** No rule to make target '@echo', needed by 'brazil'. Stop.
I was under the impression that with format, ~% encodes a newline, and ~/ encodes a tab character. But based on the error message above, it seems like at least the newline is missing from the generated recipe.
You can't do it this way, just like it won't work to have a $(shell ...) invocation define rules with multiple lines, and just like you can't use define / endef to create an entire multi-line rule then have it simply expanded with $(MY_VAR).
The expansion of a single line (like a $(guile ...) operation) cannot expand to multiple lines of output: make uses a line-oriented parser and it's already parsed this line: any subsequent newlines will be treated as ordinary spaces (not newlines).
You need to use $(eval ...) to tell make to treat the output as an actual multi-line makefile snippet. So you want:
$(eval $(guile (format #f "brazil:~%~/@echo Ere I am J.H.")))
You can also use this instead if you can put the recipe onto a single line:
$(guile (format #f "brazil: ; @echo Ere I am J.H."))
You can also put the recipe, if it must be multiline, into a variable and use:
$(guile (format #f "brazil: ; $(MY_RECIPE)"))