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uwescience / raco

Compilation and rule-based optimization framework for relational algebra. Raco is the language, optimization, and query translation layer for the Myria project.
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Allow user to specify log base #393

Open BrandonHaynes opened 9 years ago

BrandonHaynes commented 9 years ago

I have a while statement that needs to run log_2 n times. If overloading is supported, it would be nice to be able to specify a base for the existing log function. (I guess a log2 function would work as well; I find both options to be more clear than log(n) / log(2)).

dhalperi commented 9 years ago

You know that you can define little inline functions (like Lambda expressions), right?

def logN(a, b): log(a) / log(b);

will let you use logN in your program.

dhalperi commented 9 years ago

But, yes, this is a great suggestion. The place to do this is in the Expression Library: https://github.com/uwescience/raco/blob/master/raco/expression/expressions_library.py#L34

Overloading works (see SafeDiv), but I am not certain what will happen if you add a 2-ary log to the expressions library while leaving the unary log, which is in the language, alone... :) It might just work!

BrandonHaynes commented 9 years ago

Oh nice -- I did not know that the language supported inline functions. Thanks for mentioning that!

domoritz commented 9 years ago

We need docs on that. And how to write stateful apply and UDAs. I'd be happy to write the latter some time next month. Ref https://github.com/uwescience/myria-docs/blob/master/myriaql.markdown

bmyerz commented 9 years ago

@domoritz is there a issue in myria-docs to track that?

domoritz commented 9 years ago

@bmyerz No, oh I mean yes https://github.com/uwescience/myria-docs/issues/9