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

Ben Gamari ben at
Mon Dec 6 16:45:35 UTC 2021

Norman Ramsey <nr at> 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.


- Ben
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