Nim does this, it has 'proc' and 'func'. They define a `func` as a procedure with no side effects using the macro `{.noSideEffect.}` [1]. [1] https://nim-lang.

Nim does this, it has 'proc' and 'func'. They define a `func` as a procedure with no side effects using the macro `{.noSideEffect.}` [1]. [1] https://nim-lang.org/docs/manual.html#procedures-func https://nim-lang.org/docs/manual.html#procedures-func