type error when compiling an older Haskell program

[Simon Peyton-Jones]

| Add {-# OPTIONS_GHC -fno-mono-pat-binds #-}
|
| You are the fourth person to discover monomorphic pattern bindings :)

Yes, the details are here
        http://hackage.haskell.org/trac/haskell-prime/wiki/MonomorphicPatternBindings

If you could snip out the code that gave rise to the error, I'll add it to that wiki page.  (There are four other examples there, one from Koen which might perhaps be essentially the same thing.)

thanks Stefan for identifying this

Simon