[Haskell-cafe] The last statement in a 'do' construct must be an expression: a <- readArray arr (1, 1)

KC kc1956 at gmail.com
Mon Apr 23 22:52:48 CEST 2012


I'm getting the above error message and I cannot figure out why?


buildPair =
    do
arr <- newArray ((1,1),(1,10)) 37 :: ST s (STArray s (Int,Int) Int)
a <- readArray arr (1,1)
        writeArray arr (1,1) 64
        b <- readArray arr (1,1)
        return (a,b)


main = print $ runST buildPair


-- 
--
Regards,
KC
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