How to comment out lines in literate haskell
haskell, latex, literate-programming
Solution
If you're using lhs2TeX (which you seem to be), then you can hide code from LaTeX by using lhs2TeX conditionals:
%if False
> code seen by Haskell but not typeset
> -- comment that is not typeset
%endif
> code seen by Haskell and typeset
> -- comment that will be typeset
As Daniel Wagner suggests in his comment, another option is to prefix complete lines with `%` to turn them into LaTeX comments.
lhs2TeX will always treat comments as LaTeX text, but it will in addition perform preprocessing. So using a `%` on a line with a comment (as in `-- %`) is not going to work, because the `%` will be ending up in the middle of partially relevant code in the generated TeX file and trigger errors.
Problem
I am having trouble commenting out lines of code in an lhs-style haskell program, so both haskell and Latex ignore the line. When I use `--` then my lh2tex will try to render the haskell code as a comment. But this often fails, because the code contains dollars and other stuff which is confusing for Latex. When I use `--%`, then Latex is happy as it just ignores the comment, but haskell does not like `--%`. Only when I put a space after `--` haskell is okay with it, but then Latex is complaining again.