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Perl programmers may initialize a hash (or associative array) from a list of key/value pairs. If the keys are separated from the values with the => operator (sometimes called a fat comma ), rather than a comma, they may be unquoted (barewords [ 5 ] ).
Array with all the doubles from 1 to 9 inclusive: my @doubles = map { $_ * 2 } 1 .. 9 ; Array with the names of the customers based in Rio de Janeiro (from array of hashes):
Perl 5 hashes are flat: keys are strings and values are scalars. However, values may be references to arrays or other hashes, and the standard Perl 5 module Tie::RefHash enables hashes to be used with reference keys. A hash variable is marked by a % sigil, to distinguish it from scalar, array, and other data types.
In addition to support for vectorized arithmetic and relational operations, these languages also vectorize common mathematical functions such as sine. For example, if x is an array, then y = sin (x) will result in an array y whose elements are sine of the corresponding elements of the array x. Vectorized index operations are also supported.
#!usr/bin/perl – called the "shebang line", after the hash symbol (#) and ! (bang) at the beginning of the line. It is also known as the interpreter directive. # – the number sign, also called the hash symbol. In Perl, the # indicates the start of a comment. It instructs perl to ignore the rest of the line and not execute it as script code.
(pred array)/array or pred {⍵ /⍨ ⍺⍺ ⍵} array: The second example is an APL dop. C# 3.0 ienum.Where(pred) or The where clause: Where is an extension method ienum is an IEnumerable Similarly in all .NET languages CFML: obj.filter(func) Where obj is an array or a structure. The func receives as an argument each element's value. Clojure
For example, GNU grep has the following options: "grep -E" for ERE, and "grep -G" for BRE (the default), and "grep -P" for Perl regexes. Perl regexes have become a de facto standard, having a rich and powerful set of atomic expressions. Perl has no "basic" or "extended" levels.
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. This one-liner creates a function that can be used to return a list of primes up to the value of the first parameter: