I taught ghci to compile my StackOverflow posts. Can I make it slicker?

Question

Haskell Stack Overflow layout preprocessor

module StackOverflow where  -- yes, the source of this post compiles as is

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Answer 1

I would try to make a standalone preprocessor that runs SO preprocessing code or the standard literary preprocessor, depending on file extension. Then just use :set -pgmL SO-preprocessor in ghci.conf.

For the standard literary preprocessor, run the unlit program, or use Distribution.Simple.PreProcess.Unlit.

This way, :load and filename completion just work normally.

GHCI passes 4 arguments to the preprocessor, in order: -h, the label, the source file name, and the destination file name. The preprocessor should read the source and write to the destination. The label is used to output #line pragmas. You can ignore it if you don't alter the line count of the source (i.e. replace "comment" lines with -- comments or blank lines).