Comment by padator

You can use mk, the successor to make, which does not have the TAB requirement (you can use TAB or spaces interchangeably).

Regarding JSON, it is more verbose than Make. You need to use quote around strings, commands, everything. Compare:

foo.o: foo.c gcc -c foo.c

with

{ 'foo.o' => ['foo.c'; 'gcc -c foo.c'] }