Thanks! I'll try it out in a bit.

On Aug 5, 2017 10:32 PM, "Amos Robinson" <amos.robinson@gmail.com> wrote:

Yes, I believe Data.Vector.Generic.freeze will work. But I would use the one from Data.Vector.Unboxed unless you really need the generic version. Sometimes the extra constraints in the generic version can be a bit cumbersome, requiring extra type annotations where the specific versions don't.

On Sun, 6 Aug 2017 at 13:22 Cody Goodman <codygman.consulting@gmail.com> wrote:

I'm not back at a computer yet, but so I and others reading these archives in the future know: Does that mean that freeze from Data.Vector.Generic.freeze should work for me then?

On Sat, Aug 5, 2017 at 10:05 PM, Amos Robinson <amos.robinson@gmail.com> wrote:

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.html#v:freeze

On Sun, 6 Aug 2017 at 12:59 Cody Goodman <codygman.consulting@gmail.com> wrote:

I see the type is:

freeze :: (PrimMonad m, Vector v a) => Mutable v (PrimState 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-Mutable.html

Thanks,

Cody

On Sat, Aug 5, 2017 at 9:56 PM, Amos Robinson <amos.robinson@gmail.com> 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.html#v:freeze

On Sun, 6 Aug 2017 at 12:46 Cody Goodman <codygman.consulting@gmail.com> 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
-}

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