sequencefrom

SequenceFrom is a term used in programming to describe an operation that constructs a sequence starting from a given point or seed. The exact meaning varies by language and library, but it generally denotes generating a list or stream by applying a rule or selecting a portion of an existing sequence.

Common forms and signatures include several archetypes. One form creates an arithmetic or geometric progression from a start value with a step or ratio, producing a fixed-length sequence. Another form selects a subsequence from an existing sequence, starting at a specified index. A third form generates an infinite or lazily evaluated sequence by repeatedly applying a function to a current value, yielding successive elements as needed.

Examples in pseudocode illustrate these ideas. A progression form might be sequenceFrom(start, step, n) returning [start, start+step, ..., start+(n-1)step]. A subsequence form could be sequenceFrom(sequence, index) returning the tail starting at index. An iterative form uses a seed and a generator function: sequenceFrom(seed, f, n) producing [seed, f(seed), f(f(seed)), ..., n elements].

Implementation considerations include lazy vs. eager evaluation and language support. In lazy contexts, sequenceFrom can produce infinite sequences without computing all elements up front, while in eager contexts, it yields a finite list immediately. Because the name is used across libraries with different signatures, consulting specific documentation is advisable to confirm parameters and behavior.

Related concepts include range and generator functions, iterators, and streaming pipelines. See also: sequence, range, generator, and tail.