bmakelib (which is a minimalist standard library for GNU Make) v0.8.0 was released last week.

The highlight of the release is the ability to use maps/dictionaries in your makefiles!

Here's the example from the release page:

$(call bmakelib.dict.define,THIS_BUILD)
$(call bmakelib.dict.put,THIS_BUILD,arch,x86_64)
$(call bmakelib.dict.put,THIS_BUILD,dir,/tmp/my-app/build)

some-target :
	@echo BUILD.arch = $(call bmakelib.dict.get,BUILD,arch)  # x86_64
	@echo BUILD.arch = $(call bmakelib.dict.get,BUILD,dir)   # /tmp/my-app/build