meaning of tuple
1. TUPLE Toyohashi University Parallel Lisp Environment. A parallel Lisp based on KCL. ["Memory Management and Garbage Collection of an Extended Common Lisp System for Massively Parallel SIMD Architecture", Taiichi Yuasa, in Memory Management, IWMM92, Springer 1992, 490-507].
2. tuple In functional languages, a data object containing two or more components. Also known as a product type or pair, triple, quad, etc. Tuples of different sizes have different types, in contrast to lists where the type is independent of the length. The components of a tuple may be of different types 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 zero components, written , is known as the unit type since it has only 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 = bottom f bottom,bottom = 1 With lifted tuples, a tuple pattern is refutable. Thus in Haskell, pattern matching on tuples is the same as pattern matching on types with multiple constructors algebraic data types - the expression being matched is evaluated as far as the 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 and evaluation of a tuple will never fail to terminate though any of the components may. E. g. in Miranda: f x,y = 1 --> f bottom = 1 f bottom,bottom = 1 Thus in Miranda, any object whose type is compatible with a tuple pattern is assumed to match at the top level without evaluation - it is an irrefutable pattern. This also applies 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 their arguments then bottom,x = x,bottom = bottom for any x so matching a refutable pattern would fail to terminate if any component was bottom. tuple calculus
Related Words
tuple | tuple space smalltalk |
