Found this generator for aperiodic Penrose tile, makes a pretty picture. A JSL implementation should use recursive function calls to make it faster; expanding the string of symbols gets really slow for a really big tiling. Using transparency shows the generator code makes the same lines more than once. There is 5-way symmetry around the center. This is an 8-level deep recursion.
Update: another view, 6 levels deep, kites and darts identified and colored