I will often find my self writing things similar to: case some_value do nil -> something() "" -> something() _ -> something_else() end So in other words I have multiple match clauses that resolve to the same outcome. I makes me want to write something like: case some_value do nil | "" -> …

case some_value do value when value in [nil, ""] -> something() _ -> something_else() end

This only works kind of. 1 in [1.0] is true when I’m remembering correctly. Also sometimes you want to bind parts of the different matches. That won’t work with your guard as well. Last but not least guards can’t get compiled into a trie and therefore slow down the overall match.

[image] NobbZ: This only works kind of. 1 in [1.0] is true when I’m remembering correctly. I think your overall point is good but this is in fact false, both in matches and in the general case: iex(1)> match?(x when x in [1.0], 1) false iex(2)> 1 in [1.0] false

Ok, then I mid remembered the semantics of in. The issue of bindings still applies and the fact that guards do affect the performance as well. So 2 of 3 issues remaining.

[image] NobbZ: Ok, then I mid remembered the semantics of in. The issue of bindings still applies and the fact that guards do affect the performance as well. So 2 of 3 issues remaining. To be specific, the right argument of the in/not in operator must be statically known at compile-time when …

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Pattern match with multiple match options

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beno November 7, 2017, 2:59pm 3

Thank you very much. I will be using this from now on.