Re: is there a way to alter every line of an SDoc?

Norman Ramsey writes:

I'm emitting code in which I want to prettyprint the contents of a Cmm Block as a comment, by which I mean putting `--` to the left of *each* line of the rendered Cmm Block. Using GHC.Utils.Outputable, is this even possible? How would I tackle it? (The Haddock page does not suggest any obvious combinators.)

It's not easy. One (rather horrible) approach would be to render the document to a string, split the output into lines and add the comment symbols, and then splice the result into another document. Perhaps you could rather use block comment syntax? This would be much easier. Cheers, - Ben