Re: Merging the OpenGLRaw and gl packages

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On Wed, Sep 30, 2015 at 6:38 PM Sven Panne <[email protected]> wrote:

> IMHO using pattern synonyms vs. plain old Haskell values is to a large
> part just bikeshedding, at least in the trivial case at hand where we talk
> about simple integral values. It basically boils down to the question: Is
>
>    foo x = case x of
>      GL_BAR -> expr1
>      GL_BAZ -> expr2
>      _ -> expr3
>
> really so much better than
>
>    foo x
>      | x == GL_BAR = expr1
>      | x == GL_BAZ = expr2
>      | otherwise = expr3
>

Yes, because the first approach is an expression that you can use anywhere.
Sure, there's little difference when you do it at the "top" of a function
definition, as you're doing. However, it's a lot more significant if you
want to do something like:

foo x = doSomething (case x of ...)

Without pattern synonyms, you either have

foo x = doSomething x'
  where x' | x == ... = ...

or

{-# LANGUAGE MultiWayIf #-}

foo x = doSomething (if | x == ... -> ...)

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<div dir=3D"ltr"><div class=3D"gmail_quote"><div dir=3D"ltr">On Wed, Sep 30=
, 2015 at 6:38 PM Sven Panne &lt;<a href=3D"mailto:[email protected]">sve=
[email protected]</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" =
style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><di=
v dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote">IMHO us=
ing pattern synonyms vs. plain old Haskell values is to a large part just b=
ikeshedding, at least in the trivial case at hand where we talk about simpl=
e integral values. It basically boils down to the question: Is<br></div></d=
iv></div><div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_qu=
ote"><div><br></div><div>=C2=A0 =C2=A0foo x =3D case x of</div><div>=C2=A0 =
=C2=A0 =C2=A0GL_BAR -&gt; expr1</div><div>=C2=A0 =C2=A0 =C2=A0GL_BAZ -&gt; =
expr2</div><div>=C2=A0 =C2=A0 =C2=A0_ -&gt; expr3</div><div><br></div><div>=
really so much better than</div><div><br></div><div>=C2=A0 =C2=A0foo x</div=
><div>=C2=A0 =C2=A0 =C2=A0| x =3D=3D GL_BAR =3D expr1</div><div><div>=C2=A0=
 =C2=A0 =C2=A0| x =3D=3D GL_BAZ =3D expr2</div></div><div>=C2=A0 =C2=A0 =C2=
=A0| otherwise =3D expr3</div></div></div></div></blockquote><div><br></div=
><div>Yes, because the first approach is an expression that you can use any=
where. Sure, there&#39;s little difference when you do it at the &quot;top&=
quot; of a function definition, as you&#39;re doing. However, it&#39;s a lo=
t more significant if you want to do something like:</div><div><br></div><d=
iv>foo x =3D doSomething (case x of ...)</div><div><br></div><div>Without p=
attern synonyms, you either have</div><div><br></div><div>foo x =3D doSomet=
hing x&#39;</div><div>=C2=A0 where x&#39; | x =3D=3D ... =3D ...</div><div>=
<br></div><div>or</div><div><br></div><div>{-# LANGUAGE MultiWayIf #-}</div=
><div><br></div><div>foo x =3D doSomething (if | x =3D=3D ... -&gt; ...)</d=
iv></div></div>

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