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Why are side-effects modeled as monads in Haskell?
...re functions together
We defined a function impurify :: a -> IO a which converts a pure value to impure.
Now we make the identification (>>=) = (~~~) and return = impurify, and see? We've got a monad.
Technical note
To ensure it's really a monad, there's still a few axioms which need to b...
Force re-download of release dependency using Maven
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It's also possible to selectively delete the dependencies that you know need to be refreshed from inside the repository. A manual purge, if you will.
– jpaugh
Jul 27 '16 at 14:56
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Why doesn't C# support the return of references?
...e collection story. Also the "managed reference to variable" types are not convertible to object, and therefore may not be used as type arguments to generic types or methods.)
Commenter "RPM1984" for some reason asked for a citation for this fact. RPM1984 I encourage you to read the CLI specificat...
jQuery: count number of rows in a table
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Use a selector that will select all the rows and take the length.
var rowCount = $('#myTable tr').length;
Note: this approach also counts all trs of every nested table!
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How to add include path in Qt Creator?
...path>
If you are using your own build system, you create a project by selecting "Import of Makefile-based project". This will create some files in your project directory including a file named <your project name>.includes. In that file, simply list the paths you want to include, one per...
count the frequency that a value occurs in a dataframe column
...iple columns in a df
[my_series[c].value_counts() for c in list(my_series.select_dtypes(include=['O']).columns)]
https://stackoverflow.com/a/28192263/786326
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Add a prefix string to beginning of each line
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You can use Vim in Ex mode:
ex -sc '%s/^/prefix/|x' file
% select all lines
s replace
x save and close
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What's the difference between EscapeUriString and EscapeDataString?
...de the "+" characters, it just left them as is, EscapeDataString correctly converted them to "%2B".
– BrainSlugs83
Nov 10 '13 at 3:42
7
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Extract value of attribute node via XPath
...ou ignore the Parent node altogether and use:
//child/@name
you can select name attribute of all child nodes in one go.
name="Child_2"
name="Child_4"
name="Child_1"
name="Child_3"
name="Child_1"
name="Child_2"
name="Child_4"
name="Child_3"
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How to search file text for a pattern and replace it with a given value
...en you try to mv the file across a device mount you will transparently get converted to cp behavior. The old file will be opened, the old files inode will be preserved and reopened and the file contents will be copied. This is most likely not what you want, and you may run into "text file busy" err...