Documentation

This function applies a String to String function to a certain String (everything in the context of the module Prelude).

It is expensive as it calls ghc to produce its results. It has been created to formally provide the mode 'apply-to' but text editors should instead use ghc directly. The first argument control whether a warning message describing this fact is contained in the result. If it is False then the second tuple element of the result will contain an according warning otherwise it Nothing.

The result is a tuple of which the first elements contains the (stdout-)output of the call to the ghc and the second element may contain warning messages. If the first function argument is False then the second tuple element will never be Nothing. Otherwise it may be Nothing or contain a messages (for example when the executable GHC isn'f found).