stream.el provides an implementation of streams, implemented as delayed evaluation of cons cells.

stream.el requires Emacs >= 25.1.

Functions defined in seq.el can also take a stream as input.

Streams could be created from any sequential input data:

• sequences, making operation on them lazy
• a set of 2 forms (first and rest), making it easy to represent infinite sequences
• buffers (by character)
• buffers (by line)
• buffers (by page)
• IO streams
• orgmode table cells
• ...

All functions are prefixed with "stream-". All functions are tested in test/stream-tests.el

Here is an example implementation of the Fibonacci numbers implemented as in infinite stream:

(defun fib (a b)
  (stream-cons a (fib b (+ a b))))
(fib 0 1)

As well as working all functions defined in seq.el, stream.el provides the following stream-specifec functions:

• stream src

  This function returns a new stream from src. This generic method can be extended, and supports out of the box lists, strings, arrays and buffers as input.

• stream-cons first rest

  This macro returns a stream built from the cons of first and rest. first and rest are forms and rest must return a stream.

• seq-make body

  This macro returns a stream built from body. body must return nil or a cons cell, which cdr is itself a stream.

Since this library is in GNU ELPA, contributors must have signed the Emacs Copyright assignment.

Fetch dependencies:

$ cd /path/to/stream.el
$ cask

Run the tests:

$ ./run-tests.sh