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by aweinstock
3039 days ago
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> not all assignment makes a function impure That's exactly what the ST monad/STRef's are for. {new,read,write}STRef let you manipulate mutable references while keeping track of their scope in the type of the reference. runST encapsulates a chunk of code that manipulates mutable variables in an externally-pure way into a pure function. The "Lazy Functional State Threads"[1] paper on it is a pretty good read. [1]: https://www.microsoft.com/en-us/research/wp-content/uploads/... |
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