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Questions - starray

Two almost identical functions using STArray: why does one requires FlexibleContexts, and the other does not?

Consider the Haskell functions test :: ST s [Int] test = do arr <- newListArray (0,9) [0..9] :: ST s (STArray s Int Int) let f i = do writeArray arr i (2*i) readArray arr i...
test-img

Mark Wildon

arrays

haskell

state-monad

starray

Votes: 0

Answers: 1

Latest Answer

You can check which type GHC assigns to f in GHCi: ghci> import Data.Array ghci> import Data.Array.MArray ghci> let arr :: STArray s Int Int; arr = undefined ghci> :t \i -> do writeArra...
test-img

Noughtmare

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