[Haskell-cafe] When using Cereal, what is the right way to write `get` for multi-constructor type?

[William Yager]

You may also want to use the Lambda-case extension. It will allow you to
elide the declaration of i.

--Will Yager

On Tue, Apr 26, 2016 at 1:24 AM, Ivan Lazar Miljenovic <
ivan.miljenovic at gmail.com> wrote:

> On 26 April 2016 at 15:39, Magicloud Magiclouds
> <magicloud.magiclouds at gmail.com> wrote:
> > Hi,
> > Say I have code already like:
> > data STH = A
> >         | B
> >         | C
> > instance Serialize STH where
> >   put A = putWord8 1
> >   put B = putWord8 66
> >   put C = putWord8 111
> >
> > Then what is the better way to do `get`? Is following the only one?
> > get = do
> >   i <- getWord8
> >   case i of
> >     1 -> return A
> >     66 -> return B
> >     111 -> return C
>
> I think that covers it, though having an explicit error message for
> any other value of `i` will probably be better than the default
> unmatched case one.
>
> >
> > Thanks.
> >
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>
>
>
> --
> Ivan Lazar Miljenovic
> Ivan.Miljenovic at gmail.com
> http://IvanMiljenovic.wordpress.com
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