• simonmar's avatar
    [project @ 2003-01-24 14:04:40 by simonmar] · b429adbb
    simonmar authored
    - Generalise seq to allow an unlifted type in its second argument.  This
      works because seq is *always* inlined and replaced by a case.
    
    - Remove getTag, a wired-in Id with an unfolding, with a definition
      in GHC.Base:
    
    	getTag x = x `seq` dataToTag# x
    
      this is why we required the above generalisation to seq (dataToTag#
      returns an Int#).  See the comments in GHC.Base for more details.
    
    - As a side-effect, this fixes a bug in the interpreter, where the
      compiler optimised away the evaluation of the argument to dataToTag#,
      but the interpreter ended up passing it an unevaluated thunk (nullary
      constructors aren't always evaluated in GHCi, but the simplifier
      assumes they are).  Now, in the interpreter, getTag won't be inlined
      so the compiler can't optimise away the evaluation, and we're saved.
    
      The real bug here is either (a) dataToTag# requires an evaluated
      argument or (b) the interpreter doesn't supply it with one, take your
      pick.
    b429adbb