I tried once to write about this, but I gave up in the end, as the rules are somewhat diffuse. Basically, you’ll have to get the hang of it. Perhaps it is best to concentrate on where curly braces and parenthesis can be used interchangeably: when passing parameters to method calls. You may replace parenthesis … Read more
Let’s start with a code example: foob :: forall a b. (b -> b) -> b -> (a -> b) -> Maybe a -> b foob postProcess onNothin onJust mval = postProcess val where val :: b val = maybe onNothin onJust mval This code doesn’t compile (syntax error) in plain Haskell 98. It requires … Read more
In a case statement, a , is the equivalent of || in an if statement. case car when ‘toyota’, ‘lexus’ # code end Some other things you can do with a Ruby case statement
it means ‘nothing for the first argument, nothing for the second, and jump by three’. It gets every third item of the sequence sliced. Extended slices is what you want. New in Python 2.3
>> /dev/null redirects standard output (stdout) to /dev/null, which discards it. (The >> seems sort of superfluous, since >> means append while > means truncate and write, and either appending to or writing to /dev/null has the same net effect. I usually just use > for that reason.) 2>&1 redirects standard error (2) to standard … Read more
The else clause is only executed when your while condition becomes false. If you break out of the loop, or if an exception is raised, it won’t be executed. One way to think about it is as an if/else construct with respect to the condition: if condition: handle_true() else: handle_false() is analogous to the looping … Read more
open is a new access level in Swift 3, introduced with the implementation of SE-0117 Allow distinguishing between public access and public overridability It is available with the Swift 3 snapshot from August 7, 2016, and with Xcode 8 beta 6. In short: An open class is accessible and subclassable outside of the defining module. … Read more
For reference—future Python possibilities: Starting with Python 2.6 you can express binary literals using the prefix 0b or 0B: >>> 0b101111 47 You can also use the new bin function to get the binary representation of a number: >>> bin(173) ‘0b10101101′ Development version of the documentation: What’s New in Python 2.6
My view is to always use ++ and — by themselves on a single line, as in: i++; array[i] = foo; instead of array[++i] = foo; Anything beyond that can be confusing to some programmers and is just not worth it in my view. For loops are an exception, as the use of the increment … Read more
Update – 2020 Since this question was asked almost ten years ago, quite a bit has changed in Python itself since then. While the approach in my original answer is still valid for some cases, (e.g. legacy projects stuck to older versions of Python and cases where you really need to handle dictionaries with very … Read more