Hi Rob, The constant table item constants are somewhat of a legacy. The original constants were chosen to correspond to nhc's constants, however as far as the Yhc runtime is concerned: - A and Z are simply references to heap nodes and are treated in exactly the same way. - F, 0, C, P, X are all references to Info structures and are also treated in exactly the same way. However, you are quite right, looking at the C code 0 is mistakenly included with the A&Z code. This has likely not proved a problem because '0' is infact entirely redundant. The only thing you could do with a 0-arity FInfo is make an application to it, but why would you want to when you can just push the CAF instead? Ultimately we should tidy up the constants to a more simple - Some constant value (i, l, f, d, s) - References to heap nodes (N) - References to FInfo or CInfo (I) For the moment I shall change the C code to make using '0' an error :-) Thanks Tom Robert Dockins wrote:
The HBC bytecode format has different constant tags for the folloing:
1) CAF, tag 'A' 2) 0-arity function, tag '0'
http://haskell.org/haskellwiki/Yhc/RTS/hbc
Why the distinction? Maybe I don't fully understand, but I thought that a 0-arity function _was_ a CAF?
The runtime seems to treat them very much the same (although I can't be quite sure -- reading C gives me a headache ;)
Rob Dockins _______________________________________________ Yhc mailing list Yhc@haskell.org http://www.haskell.org//mailman/listinfo/yhc