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

[Cody Goodman]

I see the type is:

freeze :: (PrimMonad
<https://hackage.haskell.org/package/primitive-0.6.2.0/docs/Control-Monad-Primitive.html#t:PrimMonad>
m, Vector
<https://hackage.haskell.org/package/vector-0.12.0.1/docs/Data-Vector-Generic.html#t:Vector>
v a) => Mutable
<https://hackage.haskell.org/package/vector-0.12.0.1/docs/Data-Vector-Generic.html#t:Mutable>
v (PrimState
<https://hackage.haskell.org/package/primitive-0.6.2.0/docs/Control-Monad-Primitive.html#t: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 at 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 at 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
>> -}
>> _______________________________________________
>> 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.
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/haskell-cafe/attachments/20170805/4b8daf89/attachment.html>