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lenses, fclabels, data-accessor - which library for structure access and mutation is better
...f these libraries also provide a bunch of extra combinators on top, and usually some form of template haskell machinery to automatically generate lenses for the fields of simple record types.
With that in mind, we can turn to the different implementations:
Implementations
fclabels
fclabels is pe...
Union of dict objects in Python [duplicate]
...yptic, and it immediately makes most readers balk and the remainder assume all the keys in x would have to be legal parameter names. IMHO, the fact it works is a bug in the name-checking mechanisms in the implementation. What happens when you rely on bugs? They either get fixed, or become politic...
Deleting rows with MySQL LEFT JOIN
...ed May 4 '10 at 6:26
Daniel VassalloDaniel Vassallo
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Initializing a static std::map in C++
... Every time I see something like that done with C++, I think of all the horrendous template code that must be behind it. Good example!
– Greg Hewgill
Sep 26 '08 at 10:22
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Git cherry pick vs rebase
... the distinction indeed became somewhat moot, but this is something to be called convergent evolution ;-)
The true distinction lies in original intent to create both tools:
git rebase's task is to forward-port a series of changes a developer has in their private repository, created against versio...
What Every Programmer Should Know About Memory?
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So, any book or article that describes something fundamental cannot be called outdated. "What every programmer should know about memory" is definitely worth to read, but, well, I don't think it's for "every programmer". It's more suitable for system/embedded/kernel guys.
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Difference between Django's annotate and aggregate methods?
...rage_price': 34.35}
Returns a dictionary containing the average price of all books in the queryset.
Annotation
>>> q = Book.objects.annotate(num_authors=Count('authors'))
>>> q[0].num_authors
2
>>> q[1].num_authors
1
q is the queryset of books, but each book has been...
Select first row in each GROUP BY group?
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On Oracle 9.2+ (not 8i+ as originally stated), SQL Server 2005+, PostgreSQL 8.4+, DB2, Firebird 3.0+, Teradata, Sybase, Vertica:
WITH summary AS (
SELECT p.id,
p.customer,
p.total,
ROW_NUMBER() OVER(PARTITION BY p.cus...
What is a higher kinded type in Scala?
...pply to value arguments to "construct" a value.
Value constructors are usually called "functions" or "methods". These "constructors" are also said to be "polymorphic" (because they can be used to construct "stuff" of varying "shape"), or "abstractions" (since they abstract over what varies between ...
Cast Int to enum in Java
... 0 or 1, i.e. a valid ordinal for that enum.
Note that in Java enums actually are classes (and enum values thus are objects) and thus you can't cast an int or even Integer to an enum.
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