simple loop over files in some directory makefile

Maybe you can do it purely Makefile way?

MYDIR = .
list: $(MYDIR)/*
        @echo $^

You can still run command from Makefile like this

MYDIR = .
list: $(MYDIR)/*
        for file in $^ ; do \
                echo "Hello" $${file} ; \
        done

If I were you, I'd rather not mix Makefile and bash loops based on $(shell ...). I'd rather pass dir name to some script and run loop there - inside script.

Here is the edited answer based on @Oo.oO:

$ cat makefile
BASEDIR = ${HOME}/Downloads
MYDIR = ${BASEDIR}/ddd
all:
    @for f in $(shell ls ${MYDIR}); do echo $${f}; done

$ make
d.txt
m.txt

Also almost "true way" from documentation

TEMPLATES_DIR = ./somedir

list: 
    $(foreach file, $(wildcard $(TEMPLATES_DIR)/*), echo $(file);)