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Posible, but super ugly and unreadable. (Compare and contrast it with JavaScript; someone posted it.) map & filter work great when one can chain methods (no ma

• carapace 8y ago
  > Posible, but super ugly and unreadable. That's your aesthetic opinion. Mine happens to be the opposite: I find that code (the second Python snippet) to be elegant and readable. > (Compare and contrast it with JavaScript; someone posted it.) let result = tree.map(node => node.find(SOME_XPATH)).filter(Boolean).map(node => node.get("value")); F0 = lambda node: node.find(SOME_XPATH) F1 = lambda node: node.get("value") result = map(F1, filter(None, map(F0, tree))) Yeah, the lambdas look like lambdas; the pattern is map.filter.map; all thoughts are tidy; F1 and F2 are generic in the node type and reusable, they look like the start of a simple combinator library for nodes. All in all, I like the Python code. Even if you do this: let F0 = node => node.find(SOME_XPATH); let F1 = node => node.get("value"); result = tree.map(F1).filter(Boolean).map(F2); (Is it "let" or "var" these days?) I would say that, although the syntax seems cooler, the Python code is more conceptually elegant because map() and filter() aren't methods of a tree class. But the real gem would be Joy code: F == [SOME_XPATH find] map [bool] filter ["value" get] map Joy is the best language. A Joy compiler would be able to "open up" map and filter and write a version of F that did all the work in a single iteration. I'm actually going to be switching from Python 2 to Joy rather than Python 3, FWIW.