Use hPutStrLn for tracing.  Use of debug tracing causes the error flag to be set in the message window, which is misleading.
Use hPutStrLn for tracing.  Use of debug tracing causes the error
flag to be set in the message window, which is misleading.

alphalambda/codeworld,alphalambda/codeworld,pranjaltale16/codeworld,tgdavies/codeworld,google/codeworld,google/codeworld,pranjaltale16/codeworld,pranjaltale16/codeworld,tgdavies/codeworld,alphalambda/codeworld,google/codeworld,tgdavies/codeworld