b needs a type. [code] Prelude Data.Array.IArray> :t array array :: (Ix i, IArray a e) => (i, i) -> [(i, e)] -> a i e Prelude Data.Array.IArray> let b = array (1,33) [(i,False) | i <- [1..33]] :: Array Int Bool Prelude Data.Array.IArray> :t b b :: Array Int Bool Prelude Data.Array.IArray> b array (1,33) [(1,False),(2,False),(3,False),(4,False),(5,False),(6,False),(7,False),(8,False),(9,False),(10,False),(11,False),(12,False),(13,False),(14,False),(15,False),(16,False),(17,False),(18,False),(19,False),(20,False),(21,False),(22,False),(23,False),(24,False),(25,False),(26,False),(27,False),(28,False),(29,False),(30,False),(31,False),(32,False),(33,False)] Prelude Data.Array.IArray> [/code] the error said: No instance for (IArray ...) arising from use of `array' the unspecified type of b did not had this instance; but now it has the type "Array" --and with that type the needed instance, too. - marc Am Samstag, 16. Dezember 2006 12:56 schrieb Maurício:
Hi,
I'm trying this in ghci:
let b = array (1,33) [(i,False) | i <- [1..33]]
after :m Data.Array.IArray. It gives me that error message:
<interactive>:1:8: No instance for (IArray a Bool) arising from use of `array' at <interactive>:1:8-12 Probable fix: add an instance declaration for (IArray a Bool) In the definition of `b': b = array (1, 33) ([(i, False) | i <- [1 .. 33]])
Why?
Thanks, Maurício
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