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Date: Tue, 14 Apr 2009 22:37:49 -0400
Message-ID: <891bd3390904141937l571e34bfgbc6cd69378cca61a@mail.gmail.com>
Subject: Re: [Caml-list] pattern matching and records vs tuples
From: Yaron Minsky <yminsky@gmail.com>
To: Pal-Kristian Engstad <pal_engstad@naughtydog.com>
Cc: Yoann Padioleau <padator@wanadoo.fr>,
	"caml-list@inria.fr" <caml-list@inria.fr>
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On Tue, Apr 14, 2009 at 9:46 PM, Pal-Kristian Engstad <
pal_engstad@naughtydog.com> wrote:

>  Honestly, I'd prefer to have to annotate non-exhaustive records:
>
>     let { foo = foo; bar = bar } = x
>
> should only match { foo; bar }, but
>
>     let { foo = foo; bar =  bar; .. } = x,
>
> can match records with more labels.
>

You're right, that seems way better.  The syntax is really much clearer, and
I like exhaustiveness as the default.  The only problem is that it is
inconsistent with the current way the compiler behaves.  But if you add the
exhaustiveness checking only as a flag, and that flag is turned off by the
"...", then you're totally set.  That's very consistent with other checks in
the compiler, such as checks for unused variables.

I think this is a great suggestion.  I'm curious what Xavier thinks...

y

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On Tue, Apr 14, 2009 at 9:46 PM, Pal-Kristian Engstad <span dir=3D"ltr">&lt=
;<a href=3D"mailto:pal_engstad@naughtydog.com">pal_engstad@naughtydog.com</=
a>&gt;</span> wrote:<br><div class=3D"gmail_quote"><blockquote class=3D"gma=
il_quote" style=3D"border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0=
pt 0pt 0.8ex; padding-left: 1ex;">



 =20

<div bgcolor=3D"#ffffff" text=3D"#000000">
Honestly, I&#39;d prefer to have to annotate non-exhaustive records:<div cl=
ass=3D"im"><br>
<br>
=A0=A0=A0 let { foo =3D foo; bar =3D bar } =3D x <br>
<br></div>
should only match { foo; bar }, but <br>
<br>
=A0=A0=A0 let { foo =3D foo; bar =3D=A0 bar; .. } =3D x,<br>
<br>
can match records with more labels.</div></blockquote><div><br>You&#39;re r=
ight, that seems way better.=A0 The syntax is really much clearer, and I li=
ke exhaustiveness as the default.=A0 The only problem is that it is inconsi=
stent with the current way the compiler behaves.=A0 But if you add the exha=
ustiveness checking only as a flag, and that flag is turned off by the &quo=
t;...&quot;, then you&#39;re totally set.=A0 That&#39;s very consistent wit=
h other checks in the compiler, such as checks for unused variables.<br>
<br>I think this is a great suggestion.=A0 I&#39;m curious what Xavier thin=
ks...<br><br>y<br></div></div><br>

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