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This simple program in literate haskell, using markdown in the comments gives unlit problems:

### Ok so lets try this again.

### A page that loads and compiles:

> myfact 0 = 1  
> myfact n = n * n-1

Lets see if it works!

If I run unlit and collect the output I can see where it went wrong:

$ ~/lib/ghc-7.0.1/unlit Main.lhs Main.lpp
$ cat Main.lpp
### Ok so lets try this again.

### A page that loads and compiles:

  myfact 0 = 1  
  myfact n = n * n-1

When I look through the source code of unlit.c I think the place to check for this would be here:

    if ( c == '#' ) {
      if ( ignore_shebang ) {
         c1 = egetc(istream);
         if ( c1 == '!' ) {
           while (c=egetc(istream), !isLineTerm(c)) ;
           return SHEBANG;
         }
         myputc(c, ostream);
         c=c1;
      }
      if ( leavecpp ) {
        myputc(c, ostream);
        while (c=egetc(istream), !isLineTerm(c))
            myputc(c,ostream);
        myputc('\n',ostream);
        return HASH;
      }
    }

It seems that cabal has a similar unlit function: http://www.haskell.org/ghc/docs/latest/html/libraries/Cabal-1.10.0.0/src/Distribution-Simple-PreProcess-Unlit.html\#unlit

I haven't tested it but, I think the cabal version would handle this case correctly (or be easier to fix than a C program from 1990). Would it be possible/wise/feasible to extract the cabal version and make it a permanent replacement for the current unlit.c code?

Trac metadata

Trac field	Value
Version	7.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC	dagitj@gmail.com
Operating system
Architecture