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3 points by eds 6136 days ago | link | parent

This is probably a horribly inefficient way to implement this... but couldn't you just copy all the variables before executing the body?

Assuming

  (= a (table 'foo 'bar))
then a line like this

  (no-side-effects (= a!foo 'baz) a)
might be converted to something roughly like this

  (let a (copy a)
    (= a!foo 'baz)
    a)
a is unchanged after evaluation because the let made a deep copy that overshadowed the global value of a.

You would still have to think about constructs like def and mac, but at least this deals with shared structure of lists and tables.

Maybe something like http://arclanguage.org/item?id=3572 ?