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In the Perl programming language, autovivification is the automatic creation of new arrays and hashes as required every time an undefined value is dereferenced. Perl autovivification allows a programmer to refer to a structured variable, and arbitrary sub-elements of that structured variable, without expressly declaring the existence of the ...
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.
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.
λProlog (a logic programming language featuring polymorphic typing, modular programming, and higher-order programming) Oz, and Mozart Programming System cross-platform Oz; Prolog (formulates data and the program evaluation mechanism as a special form of mathematical logic called Horn logic and a general proving mechanism called logical resolution)
Folds can be regarded as consistently replacing the structural components of a data structure with functions and values. Lists, for example, are built up in many functional languages from two primitives: any list is either an empty list, commonly called nil ([]), or is constructed by prefixing an element in front of another list, creating what is called a cons node ( Cons(X1,Cons(X2,Cons ...
Array.iter (fun item-> instructions) array or List.iter (fun item-> instructions) list: F#: while condition do Tab ↹instructions — for i = first to last do Tab ↹instructions: foritem in set do Tab ↹instructions or Seq.iter (fun item-> instructions) set: Standard ML: while condition do ( instructions) — Array.app (fn item ...
This is an index to notable programming languages, in current or historical use. Dialects of BASIC , esoteric programming languages , and markup languages are not included. A programming language does not need to be imperative or Turing-complete , but must be executable and so does not include markup languages such as HTML or XML , but does ...
The empty hash {} is also true; in this context {} is not an empty block, because perl -e 'print ref {}' returns HASH. Evaluated boolean expressions are also scalar values. The documentation does not promise which particular value of true or false is returned. Many boolean operators return 1 for true and the empty-string for false.