[Haskell-cafe] beginners question about fromMaybe

Nico Rolle nrolle at web.de
Tue Jun 2 18:59:43 EDT 2009

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
            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?

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