How are mutable arrays implemented in Haskell?

Asked 2011-04-24T20:34:29.257

I've read many research papers on this topic, and they usually argue that arrays are implemented using Monads. But none of these papers gave a clear definition of how the "type" Array itself should be defined, they only gave definitions for the functions using monads to access or modify this type. How are arrays, having O(1) time to access or modify an indexed element, implemented in Haskell ?! (such as STUArray and MArray)

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As something of an aside, please keep in mind that "implemented using monads", as can be done for various control structures, is not really the same thing as "side effects isolated by monadic operations on an opaque type", as with IO or ST, where the properties of the monad merely ensure that pure code remains so.

The mutable data is provided as a runtime primitive, as Don Stewart explains; the only thing "implemented with monads" here is type safety.

answered 2011-04-24T20:53:27.217

How are mutable arrays implemented in Haskell?

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