Hi all,
Some days back Mark Shannon posted his view/proposal pattern matching on github.
While reading it I realised an intermediate step between matching and variable
assignment might do away with part of the discussion.
I wrote it in an issue with the view/proposal
(https://github.com/markshannon/pattern-matching/issues/1)
Thinking about it a bit longer, it really might be worth exploring the idea
more, so let me repeat it here:
1. In a pattern the values to match are marked with a special symbol (‘$’, ‘!’
or ‘?’ seem candidates).
2. A matching case produces a tuple of matched values. The tuple may be nested
to reflect the matched structure.
3. The tuple may be deconstructed according to the usual rules.
As an example:
example_value = Example("bar", Embedded(None, "foo"), 42, "baz")
match example_value:
case Example($, Embedded($, "foo"), 42, $) as t:
# t = ("bar”, (None, ), "baz”)
pass
case Example($, Embedded($, "foo"), 42, $) as pre, *rest:
# pre = "bar", rest = ((None, ), "baz”)
pass
alternatively:
match example_value:
case pre, *rest = t = Example($, Embedded($, "foo"), 42, $):
# pre = "bar", rest = ((None, ), "baz”)
# t = ("bar”, (None, ), "baz”)
pass
Just my $0.02
—eric
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