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PHP: a fractal of bad design (fuzzy notepad)PHP: a fractal of bad design (fuzzy notepad)Posted Apr 20, 2012 1:13 UTC (Fri) by mmorrow (subscriber, #83845)In reply to: PHP: a fractal of bad design (fuzzy notepad) by mmorrow Parent article: PHP: a fractal of bad design (fuzzy notepad)
Here's a better example:
The "elements" are C stmts thought of as mappings of memory configurations, and the binary operator is `;`. This is a monoid with identity element the empty C stmt.
Define,
modify(S) := the set of memory locations statement S *may* modify.
So now, `;` is commutative for every pair of statements S,T which *must not* (i.e. cannot under any possible dynamic execution path) modify one or more of the same memory locations.
(S ; T)===(T ; S) <==> modify(S)/\modify(T)==empty_set
(where "===" := equivalence wrt effect on memory)
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PHP: a fractal of bad design (fuzzy notepad) Posted Apr 20, 2012 1:37 UTC (Fri) by mmorrow (subscriber, #83845) [Link]
Actually that's not quite correct, it's more like:
(S ; T)===(T ; S)
or something along these lines, but the idea is clear.
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