Ah, that explains everything! Thank you :)
On Thursday, March 9, 2017 at 6:50:45 AM UTC-5, Michał Muskała wrote:
>
> when is an operator - it behaves very similar to operators like == or in.
>
> iex(1)> quote(do: 1 when 2)
> {:when, [], [1, 2]}
> iex(2)> quote(do: 1 == 2)
> {:==, [context: Elixir, import: Kernel], [1, 2]}
>
> In case of def, the left side (of the operator) is the call and right the
> guards.
>
> Michał.
>
> On 9 Mar 2017, 12:42 +0100, Brian Cardarella <[email protected]
> <javascript:>>, wrote:
>
> If I quote the following:
>
>
> Code.string_to_quoted """
> if foo do
> "true"
> else
> "false"
> end
> """
>
> I get the following AST:
>
> {:if, [line: 1], [{:foo, [line: 1], nil}, [do: "true", else: "false"]]}
>
> Which makes sense to me as the last node is a list. However, `when` seems
> to follow different rules and I'm not following exactly how Elixir parses
> it from the AST:
>
> Code.strig_to_quoted """
> def foo(bar) when bar == 1 do
> "baz"
> end
> """
>
> {:def, [line: 1],
> [{:when, [line: 1],
> [{:foo, [line: 1], [{:bar, [line: 1], nil}]},
> {:==, [line: 1], [{:bar, [line: 1], nil}, 1]}]}, [do: "baz"]]}
>
> `when` is not in that last list, but is now the first element in the
> values for `:def`
>
> Can someone point me to examples of how Elixir is parsing `when` within
> the source? I dug around in Kernel which brought me to elixir_def but got
> stuck there.
>
> Use case: I am experimenting with writing some macro functions that could
> take guard clauses.
>
>
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