The second odd circumstance is best illustrated by the following transcript. Assume that /tmp/a.lhs is the text of the previous message as it was posted:
$ ghci -fglasgow-exts /tmp/a.lhs GHC Interactive, version 5.04.1, for Haskell 98. Loading package base ... linking ... done. Loading package haskell98 ... linking ... done. Compiling Main ( /tmp/a.lhs, interpreted )
/tmp/a.lhs:76: Warning: No 'main' defined in module Main Ok, modules loaded: Main. *Main> let x = \f -> fapp f (('a','b'),('c',('d','e'))) Bus error (core dumped)
Incidentally, if I enter
x = \f -> fapp f (('a','b'),('c',('d','e'))) into /tmp/a.lhs and load the file into GHCi, I get
ghc-5.04.1: panic! (the `impossible' happened, GHC version 5.04.1): rdrNameModule zddFApp
These are both instances of the same bug, which Simon P.J. fixed a couple of months ago. Unfortunately the fix isn't in the latest 5.04.3 release, but it will be in the next major release. Cheers, Simon