[erlang-questions] Random newbie stuff
Sun Nov 4 14:52:02 CET 2007
On 11/4/07, Dennis Byrne <dbyrne@REDACTED> wrote:
> Hello Ulf,
> If you have a function that is 100% predictable, couldn't there be some
> serious performance gains given that the function is frequently passed the
> same message? In other words, why put a core to work calculating the result
> you gave last time someone sent you a given message? It would be better to
> use this function to spawn a process that could use the process dictionary
> as a cache (one that would never expire).
What you're basically asking for there is memoization. It would be
interesting to have memoization supported at the language level. The
compiler/interpreter isn't smart enough to know when memoization makes the
most sense (depends on freq/range of inputs, computational complexity of
function), but the programmer probably knows. You would need a syntax for
specifying function "attributes" to the compiler/interpreter. Borrowing the
":attrib" syntax from Perl, it would look like:
somecomplexfunc(X) :memoize -> ... complex body ...
I'm guessing that analysis tools could easily throw an error at you if
you've put :memoize on a function which (directly or indirectly by calling
other funcs) makes use of mutable state.
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