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 <6cfa387a-9f7b-0cb8-2bf0-3856e2f251fb@gmail.com>
Date: Fri, 26 Mar 2021 23:58:09 +0100
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To: Rowan Tommins <rowan.collins@gmail.com>
Cc: internals@lists.php.net
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Subject: Re: [PHP-DEV] Making "match" catch exceptions
From: olleharstedt@gmail.com (=?UTF-8?Q?Olle_H=C3=A4rstedt?=)

2021-03-26 23:00 GMT+01:00, Rowan Tommins <rowan.collins@gmail.com>:
> On 26/03/2021 16:45, Olle H=C3=A4rstedt wrote:
>> That made me think of a recent
>> extension to OCaml which makes it possible to catch exceptions in a
>> match-expressions (here's one blog post about it:
>> https://blog.janestreet.com/pattern-matching-and-exception-handling-unit=
e/).
>
>
> That's an interesting idea. I wonder if it would provide a way to
> implement the "data-flow" or "expression context" exception handling I
> was discussing on a different thread recently.
>
> Looking at my previous example:
>
> try {
>     $foo =3D doSomething() + $bar;
> }
> catch ( SomeException $e ) {
>     $foo =3D $bar;
> }
>
> Would become something like this:
>
> $foo =3D match($temp =3D doSomething()) {
>     exception SomeException =3D> 0,
>     default =3D> $temp
> } + $bar;

You can't catch the value of $temp in the match-case?

    $foo =3D $bar + match (doSomething()) {
      $temp =3D> $temp,
      exception SomeException =3D> 0
    };

Olle