[ReleaseCandidat]

Interesting definition of 'pure functions':

    Pure functions by default
    V functions are pure by default, meaning that their return values are a 
    function of their arguments only, and their evaluation has no side effects 
    (besides I/O).

https://github.com/vlang/v/blob/master/doc/docs.md#pure-func...

[WithinReason]

You mean the "besides I/O" part?

[ReleaseCandidat]

Yes. A 'system language' with pure functions would be, well, unusual.