Monday, 8 June 2009

Python pains, part 3

Another thing I miss is perfect matching in in and not in operators. And when I say ‘perfect’, I mean prolog. Yes, I’m mad at python because it’s not prolog. Just take a look at this wonderful code:

Neat, eh? So, why can’t I do this, then?

(Yes, I know what the underscore variable in python is for, just pretend you don’t and roll along, ok?)

The nastiest thing about this issue is that it is not universally solvable. Once you’ve implemented a special magic matching function for this particular case, there will be someone who wants to write:

If the whole tuple on the left hand side is defined, one can do the matching perfectly in python. If some parts ain’t, one cannot and has to write an awkward external matching/traversal function. Too bad!

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