This is the important bit of code in the file: instance Outputable Demand where ppr Top = char 'T' ppr Abs = char 'A' ppr Bot = char 'B' ppr (Defer ds) = char 'D' <> ppr ds ppr (Eval ds) = char 'U' <> ppr ds ppr (Box (Eval ds)) = char 'S' <> ppr ds ppr (Box Abs) = char 'L' ppr (Box Bot) = char 'X' ppr d@(Box _) = pprPanic "ppr: Bad boxed demand" (ppr d) ppr (Call d) = char 'C' <> parens (ppr d) instance Outputable Demands where ppr (Poly Abs) = empty ppr (Poly d) = parens (ppr d <> char '*') ppr (Prod ds) = parens (hcat (map ppr ds)) You do need to be able to read the pretty printing combinators. Here's a quick cheat sheet; check http://hackage.haskell.org/packages/archive/pretty/1.0.1.0/doc/html/Text-Pre... the basic idea. char ==> print a single character <> ==> concatenate without adding a space parens x ==> put parentheses around x hcat ==> concatenate a list without adding a space Cheers, Edward Excerpts from Johan Tibell's message of Wed Mar 07 18:41:42 -0500 2012:
Edward, I have looked at that file before and it didn't make me much wiser, because I cannot map it to the output.
I find it's the parenthesis that confuses me the most. What does this mean?
C(U(LU(L)))
what about this?
U(SLLAA)LL
-- Johan