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Elliptical Python Programming

(susam.net)
183 points sebg | 1 comments | 10 Apr 25 12:53 UTC | HN request time: 0s | source
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benob ◴[10 Apr 25 14:37 UTC] No.43644247[source]▶
TIL that in python, 1--2==3
replies(1): >>43644397 #
seplox ◴[10 Apr 25 14:52 UTC] No.43644397[source]▶
It's not a python thing. 1-(-2), distribute the negative.
replies(1): >>43644519 #
qsort ◴[10 Apr 25 15:01 UTC] No.43644519[source]▶
In most C-like languages that would be a syntax error. E.g. in C and C++ as a rule you tokenize "greedily", "1--2" would be tokenized as "1", "unary decrement operator", "2", which is illegal because you're trying to decerment an rvalue.

Python doesn't have "--", which allows the tokenizer to do something else.

replies(2): >>43645088 #>>43646211 #
1. j2kun ◴[10 Apr 25 17:33 UTC] No.43646211[source]▶
Also worth noting that `1 - -2` works and produces 3 in C because the space breaks the operator.