Robert Dockins wrote:
Other have pointed out that, in the CURRENT Haskell semantics, the above is quite difficult to reason about.Or how about.... ?? lookupVarible target env = case [ v | (n,v) <- env, n==target ] of (x:_) -> x_ -> assert False $ "BUG: Unexpected variable out of scope "++(show target)++" in environment "++(show env)
Note that the whole point of Wolfram Kahl's Pattern Matching Calculus is to restore equational reasoning to pattern-matches.
http://www.cas.mcmaster.ca/~kahl/PMC/ Jacques _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
