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Python uses the following syntax to express list comprehensions over finite lists: S = [ 2 * x for x in range ( 100 ) if x ** 2 > 3 ] A generator expression may be used in Python versions >= 2.4 which gives lazy evaluation over its input, and can be used with generators to iterate over 'infinite' input such as the count generator function which ...
The split function creates a list of the parts of the string that are separated by what matches the regular expression. In this example, a line is divided into a list of its own comma-separated parts, and this list is then assigned to the @words array.
In Python, functions are first-class objects that can be created and passed around dynamically. Python's limited support for anonymous functions is the lambda construct. An example is the anonymous function which squares its input, called with the argument of 5:
Python's is operator may be used to compare object identities (comparison by reference), and comparisons may be chained—for example, a <= b <= c. Python uses and, or, and not as Boolean operators. Python has a type of expression named a list comprehension, and a more general expression named a generator expression. [77]
Perl poetry is the practice of writing poems that can be compiled as legal Perl code, for example the piece known as "Black Perl". Perl poetry is made possible by the large number of English words that are used in the Perl language. New poems are regularly submitted to the community at PerlMonks. [148]
In a dynamically typed language, where type can only be determined at runtime, many type errors can only be detected at runtime. For example, the Python code a + b is syntactically valid at the phrase level, but the correctness of the types of a and b can only be determined at runtime, as variables do not have types in Python, only values do.
PerlMonks – a community committed to sharing Perl knowledge and coding tips; Free Perl tutorials. Perl in 10 easy lessons at Linux Forums; Perl Maven Tutorial – a beginner and an advanced tutorial; Learn Perl in about 2 hours 30 minutes – introductory tutorial; Introductory Perl Tutorial Course for Windows – includes CGI instruction.
For example, the following Perl one-liner will reverse all the bytes in a file: perl -0777e 'print scalar reverse <>' filename While most Perl one-liners are imperative, Perl's support for anonymous functions, closures, map, filter (grep) and fold (List::Util::reduce) allows the creation of 'functional' one-liners.