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Map functions can be and often are defined in terms of a fold such as foldr, which means one can do a map-fold fusion: foldr f z . map g is equivalent to foldr (f . g) z . The implementation of map above on singly linked lists is not tail-recursive , so it may build up a lot of frames on the stack when called with a large list.
Scala also features the tree-like folds using the method list.fold(z)(op). [11] Scheme R 6 RS (fold-left func initval list) (vector-fold func initval vector) (fold-right func initval list) (vector-fold-right func initval vector) (reduce-left func defaultval list) (reduce-right func defaultval list) (unfold p f g seed [tail-gen]) unfold-right p ...
Scala runs on the Java platform (Java virtual machine) and is compatible with existing Java programs. [15] As Android applications are typically written in Java and translated from Java bytecode into Dalvik bytecode (which may be further translated to native machine code during installation) when packaged, Scala's Java compatibility makes it well-suited to Android development, the more so when ...
Scala normally manages the memory automatically in its JVM and JavaScript targets. However, the LLVM-based Scala Native compiler supports the use of pointers, as well as C-style heap allocation (e.g. malloc, realloc, free) and stack allocation (stackalloc). [23]
MapReduce is a programming model and an associated implementation for processing and generating big data sets with a parallel and distributed algorithm on a cluster. [1] [2] [3]A MapReduce program is composed of a map procedure, which performs filtering and sorting (such as sorting students by first name into queues, one queue for each name), and a reduce method, which performs a summary ...
A nonempty list can be implemented by a Church pair; First contains the head. Second contains the tail. However this does not give a representation of the empty list, because there is no "null" pointer. To represent null, the pair may be wrapped in another pair, giving three values: First - the null pointer (empty list). Second.First contains ...
zip() and map() (3.x) stops after the shortest list ends, whereas map() (2.x) and itertools.zip_longest() (3.x) extends the shorter lists with None items Ruby: list1.zip(list2) list1.zip(list2, list3) list1.zip(list1, .., listn) When the list being executed upon (list1) is shorter than the lists being zipped the resulting list is the length of ...
Or, via list comprehension: [x for x in list if pred(x)]. In Python 3, filter was changed to return an iterator rather than a list. [ 13 ] The complementary functionality, returning an iterator over elements for which the predicate is false, is also available in the standard library as filterfalse in the itertools module.