[Haskell-cafe] How to avoid floods of fromIntegral (in ALSA.Sequencer)

[Conal Elliott]

You can factor out the fromIntegral t part using (***) from Control.Arrow.
For functions,

> (f *** g) (x,y) = (f x, g y)

Drop time (t) handling from render:

> playSong :: DtzEvents -> IO()
> playSong events = runContT (foo "128:0" 120 (map (fromIntegral ***
render) events)) print
>   where
>     render (NoteOn c n v) = noteOn c n v
>     ...

-- Conal


On Sun, Nov 3, 2013 at 9:36 AM, martin <martin.drautzburg at web.de> wrote:

> Am 11/03/2013 03:35 PM, schrieb Niklas Hambüchen:
> > It depends a bit:
> >
> > What is supposed to happen / what happens in your library when one of
> > the numbers is larger than a Word8?
> >
> > That usually determines where / how the conversion fits in nicely.
> >
> > For example, if you already know that all the values in DtzEvent can
> > only be Word8s, then they should probably already be Word8s and not Int.
>
>
> Silly me,
>
> yes using Word8 instead of Ints got rid of most of the fromIntegrals. I
> didn't know that Word8 was an actual haskell
> type. Thought it was something private to ALSA.Sequencer.
>
> There is one remaining fromIntegral. This is "time"
>
>
>     Couldn't match expected type
> `alsa-seq-0.6.0.2:Sound.ALSA.Sequencer.Marshal.Time.Tick'
>                 with actual type `T'
>
> This seems to be realy a private thing and I found to way other than
> fromIntegral to make the compiler happy.
>
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