patch applied (ghc): Monadify typecheck/Inst: use do, return and standard monad functions

[Ian Lynagh]

Thu Jan 17 13:06:55 PST 2008  Twan van Laarhoven <twanvl at gmail.com>
  * Monadify typecheck/Inst: use do, return and standard monad functions

    M ./compiler/typecheck/Inst.lhs -83 +82