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Java 8 Streams - collect vs reduce

...t argument to the operator is the return value of the previous application and the second argument is the current stream element. collect is an aggregation operation where a "collection" is created and each element is "added" to that collection. Collections in different parts of the stream are then...
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Why does the C++ map type argument require an empty constructor when using []?

..., among other things, they should be default-constructible. Without this (and others requirements) it would be needlessly hard to implement the various internal copy/move/swap/compare operations on the data structures with which STL containers are implemented. Upon reference to the C++ Standard, ...
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Scala: What is the difference between Traversable and Iterable traits in Scala collections?

I have looked at this question but still don't understand the difference between Iterable and Traversable traits. Can someone explain ? ...
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django urls without a trailing slash do not redirect

...True, if the request URL does not match any of the patterns in the URLconf and it doesn’t end in a slash, an HTTP redirect is issued to the same URL with a slash appended. Note that the redirect may cause any data submitted in a POST request to be lost.". "The APPEND_SLASH setting is only used i...
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is node.js' console.log asynchronous?

...mat.apply(this, arguments) + '\n'); }; So it simply does some formatting and writes to process.stdout, nothing asynchronous so far. process.stdout is a getter defined on startup which is lazily initialized, I've added some comments to explain things: .... code here... process.__defineGetter__('s...
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How to convert comma-delimited string to list in Python?

...igit() else e for e in mStr.split(',')] It is called list comprehension, and it is based on set builder notation. ex: >>> mStr = "1,A,B,3,4" >>> mList = [int(e) if e.isdigit() else e for e in mStr.split(',')] >>> mList >>> [1,'A','B',3,4] ...
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Parse a .py file, read the AST, modify it, then write back the modified source code

...on source code. Basically I want to read a .py file, generate the AST , and then write back the modified python source code (i.e. another .py file). ...
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How to convert an enum type variable to a string?

...of output, you can define an operator<< that takes an enum parameter and does the lookup for you. share | improve this answer | follow | ...
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What is the difference between square brackets and parentheses in a regex?

.../^[789]\d{9}$/ /^[7-9]\d{9}$/ The explanation: (a|b|c) is a regex "OR" and means "a or b or c", although the presence of brackets, necessary for the OR, also captures the digit. To be strictly equivalent, you would code (?:7|8|9) to make it a non capturing group. [abc] is a "character class" th...
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Reference assignment operator in PHP, =&

What does the =& (equals-ampersand) assignment operator do in PHP? 4 Answers 4 ...