writeFileF :: F (String, String) (String, Either D_IOError ())
writeFileFis a fudget for writing files. It accepts pairs of file name and new contents as input, and outputs the contents.
Right (), if the write operation was successful, or
Left err, if an error occurred. The error type is
IOErroras defined for dialogue IO in Haskell 1.2.
Performing other Haskell 1.2 IO operations: haskellIOF et al.