Build a mutable vector with Data.Binary.Get

I am trying to parse a binary file into a haskell vector. I can load my file into a regular list, but since I have more than 10000000 elements for each file, I have terrible performances.

To parse the binary file, I use Data.Binary.Get and Data.Binary.IEEE754 since I intend to read float values. I am trying to build my vector as Mutable to then return it freezed.

I end up at a where I have a problem because Get is not an instance of Control.Monad.Primitive.PrimMonad which looks pretty obscure to me.

import qualified Data.ByteString.Lazy        as B
import qualified Data.Vector.Unboxed.Mutable as UM
import qualified Data.Vector.Unboxed         as U
import Data.Binary.Get
import Data.Binary.IEEE754

type MyVectorOfFloats = U.Vector Float

main = do
    -- Lazyly read the content of the file as a ByteString
    file_content <- B.readFile "vec.bin"
    -- Parse the bytestring and get the vector
    vec <- runGet (readWithGet 10) file_content :: MyVectorOfFloats
    -- Do something usefull with it...
    return ()


readWithGet :: Int
            -> Get MyVectorOfFloats -- ^ Operates in the Get monad
readWithGet n = do
    -- Initialize a mutable vector of the desired size
    vec <- UM.new n
    -- Initialize the vector with values obtained from the Get monad
    fill vec 0
    -- Finally return freezed version of the vector
    U.unsafeFreeze vec
  where
    fill v i
        | i < n = do
            -- Hopefully read one fload32 from the Get monad
            f <- getFloat32le
            -- place the value inside the vector
            -- In the real situation, I would do more complex decoding with
            -- my float value f
            UM.unsafeWrite v i f
            -- and go to the next value to read
            fill v (i + 1)
        | otherwise = return ()

The example above is quite simple, in my situation I have run-length like decoding to do, but the problem stays the same.

First, does the libraries I selected seem adequate for my use ? I currently do not really need the all vector in memory at once. I can operate on chunks. Something from pipes or Conduit looks like interesting.

Do I have to make Get an instance of Control.Monad.Primitive.PrimMonad to do what I want ?

I think I could try to do some unfolding pattern to build the vector without mutable state.