On Friday, March 10, 2017 at 8:05:47 PM UTC, Jon Zeppieri wrote:
>
> This topic must have come up in the past, but I promise that I did look
> before posting and only found limited information.
>
> Pattern-matching on records is limited to punning on the field name. That
> is, you can have a pattern like `{a, b}`, which will bind `a` to the value
> corresponding to the record's `a` label and `b` to the value... &c, &c. But
> you can't write a more general pattern like `{a = <pat1>, b = <pat2>}`.
>
> Is there some aspect of the language that makes it impossible (or
> difficult) to support these patterns? Or are they just not implemented, for
> whatever reason?
>
They would not be impossible for the compile to implement.
func { a = SomeType field } = ...
Can expand to
func { a } =
let
(SomeType field) = a
in
...
demonstrating that is just syntax sugar.
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