[cvs-nhc98] patch applied (hat): Changed definition of " undefined" so that it generates both a ConstDef and a ConstUse node and the error message points to the ConstUse node. Thus hat-explore can handle " undefined" without special consideration and for other tools such as hat-trail it doesn' t make a difference.

[Malcolm Wallace]

Thu Apr 28 11:29:19 PDT 2005  olaf
  * Changed definition of "undefined" so that it generates both a ConstDef and a ConstUse node and the error message points to the ConstUse node. Thus hat-explore can handle "undefined" without special consideration and for other tools such as hat-trail it doesn't make a difference.
  
  So special about "undefined" is that the error message points to the ConstUse, not the ConstDef. Also the ConstDef has the same parent as the ConstUse, but that is unimportant for the tools (should parent of ConstDef just be Root for consistency?).
  
  Also little change in Hat-Explore for determining the start redex when program aborted with error message. Avoids starting in trusted code, if abortion there. Not sure this actually makes a difference now that "undefined" has been changed.

    M ./src/hatlib/Hat/PreludeBuiltinTypes.hs -1 +6
    M ./src/hattools/HatExplore.hs -5 +10