Re: [Haskell-cafe] beginners question about fromMaybe

I just noticed that my suggestion doesn't work. You're testing whether val is Nothing and in my code snipped val has a different type. On 6/3/09, Raynor Vliegendhart wrote:

If you're absolutely certain that the lookup always succeeds, then you can use pattern matching as follows:

where jr = joinTuples sc x val key = getPartialTuple is x Just val = Map.lookup key m

On 6/3/09, Nico Rolle wrote:

...

hi there

heres a code snipped, don't care about the parameters. the thing is i make a lookup on my map "m" and then branch on that return value

probePhase is sc [] m = [] probePhase is sc (x:xs) m | val == Nothing = probePhase is sc xs m | otherwise = jr ++ probePhase is sc xs m where jr = joinTuples sc x (fromMaybe [] val) key = getPartialTuple is x val = Map.lookup key m

the line "jr = joinTuples sc x (fromMaybe [] val)" is kind of ugly because i know that it is not Nothing. is there a better way to solve this? regards _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe