Detect infinitely recursing grammars

[alecthomas]

Sometimes, through my own idiocy, I create infinitely recursing grammars. Debugging these can be difficult, so it would be very useful if Participle could detect them.

[idcmp]

I've done this a few times in learning participle. The first time was worrying as my sample didn't return, eventually my fan spun up into high gear and my music started stuttering.

Eventually Linux's OOM killer stepped in to help me out.

[alecthomas]

Yeah definitely not ideal :\