[Haskell-cafe] runST

[Cale Gibbard]

Not if you want a pure result. The IO monad is one-way, whereas ST has
runST to get back a result.
 - Cale

On 07/10/05, Joel Reymont <joelr1 at gmail.com> wrote:
> Folks,
>
> Why use runST in the following example at
>
> http://www.n-heptane.com/nhlab/repos/NewBinary/Tests/BinDouble.hs ?
>
> doubleToInts d = runST (
>      do arr <- newDoubleArray (1,2)
>         writeDoubleArray arr 1 d
>         i1 <- readIntArray arr 1
>         i2 <- readIntArray arr 2
>         return (i1,i2))
>
> Isn't it possible to do the same within the IO monad?
>
>      Thanks, Joel
>
> --
> http://wagerlabs.com/idealab
>
>
>
>
>
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