tuple

[′tü·pəl] (computer science) A horizontal row of data items in a relational data structure; corresponds to a record or segment in other types of data structures.

TUPLE

(1)Toyohashi University Parallel Lisp Environment

tuple

(2)In functional languages, a data object containing two ormore components. Also known as a product type or pair,triple, quad, etc. Tuples of different sizes have differenttypes, in contrast to lists where the type is independent ofthe length. The components of a tuple may be of differenttypes whereas all elements of a list have the same type.Examples of tuples in Haskell notation are (1,2),("Tuple",True), (w,(x,y),z). The degenerate tuple with zerocomponents, written (), is known as the unit type since it hasonly one possible value which is also written ().

The implementation of tuples in a language may be either"lifted" or not. If tuples are lifted then (bottom,bottom)/= bottom and the evaluation of a tuple may fail to terminate.E.g. in Haskell:

f (x,y) = 1 --> f bottom = bottomf (bottom,bottom) = 1

With lifted tuples, a tuple pattern is refutable. Thus inHaskell, pattern matching on tuples is the same as patternmatching on types with multiple constructors (algebraic data types) - the expression being matched is evaluated as far asthe top level constructor, even though, in the case of tuples,there is only one possible constructor for a given type.

If tuples are unlifted then (bottom, bottom) = bottom andevaluation of a tuple will never fail to terminate though anyof the components may. E.g. in Miranda:

f (x,y) = 1 --> f bottom = 1f (bottom,bottom) = 1

Thus in Miranda, any object whose type is compatible with atuple pattern is assumed to match at the top level withoutevaluation - it is an irrefutable pattern. This alsoapplies to user defined data types with only one constructor.In Haskell, patterns can be made irrefutable by adding a "~"as in

f ~(x,y) = 1.

If tuple constructor functions were strict in all theirarguments then (bottom,x) = (x,bottom) = bottom for any x somatching a refutable pattern would fail to terminate if anycomponent was bottom.

tuple

(1) In a relational database, a tuple is one record (one row). See record and relational database.

(2) A set of values passed from one programming language to another application program or to a system program such as the operating system. Typically separated by commas, the values may be parameters for a function call or a set of data values for a database. See function.

tuple

tu·ple

tuple

tuple

tuple

TUPLE

tuple

tuple

TUPLE