Hi > The first case makes sense, and is just a RULE. Though it seems GHC already > does this? > > g = head "" > > goes to: > > M.g = badHead @ Char > > without prompting.
Nope, as far as I can tell "" gets translated to [], not unpackCString# "" - hence the unpack never gets in the way. If you had the second rule, you'd soon want the first. > So I wondered if I could write a rule for head/unpackCString > > Urgh. not what we want though. GHC won't index the string at compile time, > and I can't write a RULE for it. Yeah, I tried that too... > Perhaps you can newtype Char and use string overloading to work around the > packing issue? That would work on GHC, but not on Hugs. Thanks Neil _______________________________________________ Glasgow-haskell-users mailing list [email protected] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
