`defpartial` and `defcurry` do not support zero arity functions without parentheses

[florius0]

Turns out, in Elixir AST if a function/0 is defined without parentheses (def function, do: nil), the arguments that are passed to macro is {:function, _, nil}, instead of {:function, _, []}, thus breaking defpartial and defcurry

[github-actions[bot]]

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