make start gdb in Emacs
file gui.o break myMult file jacekffi
run the Gud command Run
http://docs.idris-lang.org/en/latest/reference/packages.html#package-descriptions
http://docs.idris-lang.org/en/latest/reference/packages.html#binding-to-c
/msys64/usr/bin/make.exe
http://docs.idris-lang.org/en/latest/reference/ffi.html#c-callbacks
make clean make run