To answer the original question (in the subject line), "The ribbon ratio is the number of times the ribbon fits into a line. The ribbon is the number of characters on a line excluding leading and trailing white spaces. " See also the original paper on which the Text.PrettyPrint.HughesPJ code is based: http://www.cs.chalmers.se/~rjmh/Papers/pretty.ps section 7.4. The idea is that the pretty-printer should not cram lots of text into a single line, if it would look nicer split across two (shorter) lines. The ribbonsPerLine ratio is the factor that determines this level of "prettiness". A ratio of 1.0 means to cram everything into the line if you can. A larger ratio means to go for more lines, but less text on each. Somewhere between 1.2 and 1.8 is likely to be more or less pleasing: 1.0 will be ugly, 2.0 or above will look decidedly fragmented. Regards, Malcolm