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Comment by genidoi | Hacker News Reader

dic = {k: v for k, v in dic.items() if k in other_dic and v == "bar"}

How could that be improved? That's 3-4 LOC minimum in any other language

My main grip is python's ternary operators, since the True value is evaluated before the condition, if you are doing ternaries on things that might throw exceptions the False value has to come first

value = 0 if key not in dic else dic[key] * 5

rather than (throws indexerror if key isn't in dic)

value = dic[key] * 5 if key in dic else 0

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    dic = {k: v for k, v in dic.items() if k in other_dic and v == "bar"}

> "How could that be improved? That's 3-4 LOC minimum in any other language"

If I'm understanding the comprehension correctly,

    (into {} (filter (fn [[k v]] (and (get other-dic k) (= v "bar"))) dic))

Though, for readability, I'd likely write it as:

  (->> dic
       (filter (fn [[k v]]
                 (and (get other-dic k)
                      (= v "bar"))))
       (into {}))

Legibility is in the eye of the beholder.

Each to their own, but both the snippets you posted crossed my threshold for headache inducing parentheses tracking

Similarly, my parsing of special-case syntax in the Python.

What special-case syntax? The only brazenly pythonic thing in there was the (iterative) tuple unpacking, as in

(for) k, v in dic.items()

which is just

k, v = (<key>, <value>) for every key value pair in the dictionary

There are a number of precedence rules you need to keep track of to parse the list comprehension. There are two different syntaxes that do the same thing. Arguably you need to do the same if you don't already know how the threading macro in the my second example works.

I posted due to your claim regarding all other languages necessitating increased verbosity. I should have left it lie, as I didn't intend to promote a language war, just to post a counter example. My apologies.

No language war intended, just curious how something I see as a wheel could be improved.

It appears textually first but the evaluation order is the same as the classic ?: ternary. ```[][0] if False else 'foo'``` will not raise an IndexError.

I like comprehensions, but think this style has some advantages (and some disadvantages):

dic = dic.where((k, v) => k in other_dic and v == "bar").todict()

> dic = {k: v for k, v in dic.items() if k in other_dic and v == "bar"}

dic.iter().filter(|k, v| other_dic.contains(k) && v == "bar").collect();

it's one line, though I'd format it as 3 for readability (list comprehension is hard to read and functional style composes better.

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