Arrays(2) Arrays(2)
NAME
arrays: find, append, prepend, tail, pair, filter, map-
array operations
SYNOPSIS
include "arrays.m"
arrays := load Arrays Arrays->PATH;
find: fn[T](a: array of T, x: T): array of T
for { T => Equals: fn(a, b: T): int; };
append: fn[T](a₀: array of T, x: T): array of T;
prepend: fn[T](a₀: array of T, x: T): array of T;
tail: fn[T](a: array of T): array of T;
pair: fn[T₁, T₂](a₁: array of T₁, a₂: array of T₂): array of (T₁, T₂);
stringify: fn[T](a: array of T): string
for { T => String: fn(a: self T): string; };
filter: fn[T](a: array of T, f: ref fn(x: T): int): array of T;
map: fn[T](a₀: array of T, f: ref fn(x: T): T): array of T;
DESCRIPTION
The module arrays provides operations on arrays of type T,
which may be any reference type, or string. Reference types
are array, chan, array, module, and ref adt. None of the
operations change their parameter arrays: they always return
a new array.
First, there is a group of common array operations.
Find finds the first instance of x in array a and returns
the slice a[x:]. Find returns nil if there is no instance of
x in a. The type T must implement a method Equals which
returns a number greater than zero if the elements a and b
are equal and zero if a and b are not equal.
Append returns a new array with the elements of a₀ followed
by the element x.
Prepend returns a new array with the element x followed by
the elements of a₀.
Tail returns a new array which is the slice a[1:]. Nil is
returned if the length of a is less than 2 elements.
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Arrays(2) Arrays(2)
Pair takes two arrays a₁ and a₂, and returns a new array of
tuples (v1, v2) in which each element of a₁ has been paired
with the corresponding element of a₂. Nil is returned if the
arrays are not equal in length.
Stringify returns a visually pleasing string representation
of a. The type T must implement a method String which
returns a string representation of an element in the array
of type T.
A second group of operations applies a function f or a
Boolean predicate p to each element of a array, returning a
transformed array or a Boolean value. A predicate p must
return non-zero if its parameter value satisfies its condi-
tion, and must return zero if it does not.
Filter returns a new array containing only the elements of a
that satisfy p.
Map returns a new array in which each element of a₀ has been
transformed by f (ie, if a₀ is e0,e1,⋯ then the result is
f(e0),f(e1),⋯).
SOURCE
/appl/lib/arrays.b
BUGS
The current implementation of polymorphism is limited to
reference types and strings, which in turn limits use of
this module.
SEE ALSO
lists(2)
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