Re: [Haskell-cafe] Convert Data.Vector.Unboxed.Mutable.MVector to Data.Vector.Unboxed.Vector

Mutable is the type family from Vector to MVector. So the result type will be an instance of Vector, but the input MVector doesn't need to be. It's a little confusing that freeze is in Data.Unboxed.Vector, not .Mutable: https://hackage.haskell.org/package/vector-0.12.0.1/docs/Data-Vector-Unboxed... On Sun, 6 Aug 2017 at 12:59 Cody Goodman wrote:

I see the type is:

freeze :: (PrimMonad https://hackage.haskell.org/package/primitive-0.6.2.0/docs/Control-Monad-Pri... m, Vector https://hackage.haskell.org/package/vector-0.12.0.1/docs/Data-Vector-Generic... v a) => Mutable https://hackage.haskell.org/package/vector-0.12.0.1/docs/Data-Vector-Generic... v (PrimState https://hackage.haskell.org/package/primitive-0.6.2.0/docs/Control-Monad-Pri... m) a -> m (v a)

So there is a Vector constrant that MVector will not have. Does the Mutable type family get around this somehow?

There doesn't seem to be a freeze function specifically for Data.Vector.Unboxed.Mutable.MVector listed at: https://hackage.haskell.org/package/vector-0.12.0.1/docs/Data-Vector-Unboxed...

Thanks,

Cody

On Sat, Aug 5, 2017 at 9:56 PM, Amos Robinson wrote:

...

I think you want "Data.Vector.Generic.freeze", or unsafeFreeze if you are sure you won't modify the mutable vector after making it immutable.

https://hackage.haskell.org/package/vector-0.12.0.1/docs/Data-Vector-Generic...

On Sun, 6 Aug 2017 at 12:46 Cody Goodman wrote:

...

I want to do this so I can use the Data.Vector.Unboxed.Generic functions requiring the Vector constraint, namely the maxIndex function. Implementing maxIndex for Data.Vector.Unboxed.Mutable.MVector would be useful as well, but I'm even more confused at how to do that or where to begin.

Here is some stubbed out code demonstrating this.

{-# Language ScopedTypeVariables #-} module Main where

import Control.Monad.Primitive import qualified Data.Vector.Unboxed import qualified Data.Vector.Generic as VG import qualified Data.Vector.Unboxed.Mutable as VM import qualified Data.Vector.Unboxed as V

toImmutable :: VM.MVector RealWorld Int -> V.Vector Int toImmutable = undefined

main :: IO () main = do v :: VM.MVector RealWorld Int <- VM.new 1 VM.write v 0 (3 :: Int) x <- VM.read v 0 -- y <- VG.head . toImmutable $ v -- print y print $ VM.length v

{- Thanks,

Cody -} _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.