[Haskell-beginners] case statement and guarded equations

[PATRICK BROWNE]

In the case statement for the half function I think  variable m is bound to
the value of (snd (half (n - 1)).  With this assumption, I have have
written a guarded version called half1. Is it always possible to write case
statements as a set of conditional equations? My intuition is that this
should be possible and that the guarded version reduces pattern matching?

Thanks,
Pat

data EvenOdd = Even | Odd deriving (Show,Eq)
half 0 = (Even,0)
half n = case half (n-1) of (Even,m) -> (Odd,m)
                            (Odd,m) -> (Even,m+1)

half1 0  =  (Even , 0)
half1 n  |  (fst  (half (n - 1)) == Even)  = (Odd , (snd (half (n - 1))))
half1 n  |  (fst  (half (n - 1)) == Odd)   = (Even , ((snd (half (n - 1)))
+ 1))

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