Random generators

Functions to generate random numbers and data structures.

Requirenments

• emacs 27.1 higher

Features

• Predictable random number generation
• Predictable lazy random ranges generation
• Predictable random lists generation

Installation

Copy-paste plugin script contents to ~/.emacs while enabling lexical-binding

Example ~/.emacs config:

;;; -*- lexical-binding: t; -*-
(require 'package)
(add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/") t)
(package-initialize)

;; The extension file content with all comments removed can be placed here.

(custom-set-variables
;; custom-set-variables was added by Custom.
;; If you edit it by hand, you could mess it up, so be careful.
;; Your init file should contain only one such instance.
;; If there is more than one, they won't work right.
'(package-selected-packages '(markdown-mode)))
(custom-set-faces
;; custom-set-faces was added by Custom.
;; If you edit it by hand, you could mess it up, so be careful.
;; Your init file should contain only one such instance.
;; If there is more than one, they won't work right.
)

Functionality

All from, to and length parameters are optional and default to the following values respectively: 0, 100, and 10. By convention all parameters are ordered as follows:

• length, from, and to (for functions accepting random number ranges)
• sequence, and length (for functions accepting another sequence)

Functions ending with -from generate sequences or lists from items of existing sequences. Below square brackets are used to represent optional parameters and not arrays.

• Function: random-generators-number [from to] Description: Generate a number inside specific boundaries.
• Function: random-generators-sequence [length from to] Description: Generate a sequence with a specific length.
• Function: random-generators-list [length from to] Description: Generate a list with a specific length.
• Function: random-generators-sequence-from sequence [length] Description: Generate a sequence with a specific length from another one.
• Function: random-generators-sequence-from-or-empty sequence [length] Description: Try generate a sequence with a specific length from another one.
• Function: random-generators-list-from sequence [length] Description: Generate a list with a specific length from another one.
• Function: random-generators-list-from-or-empty sequence [length] Description: Try generate a list with a specific length from another one.

Examples

Generate a random number within [10..20] range:

(random-generators-number 10 20)

Generate a sequence of 5 random numbers within [10..20] range:

(iter-do (item (random-generators-sequence 5 10 20)) (message (format "item is %d" item)))

Generate a list of 5 random numbers within [10..20] range:

(random-generators-list 5 10 20)

Generate a sequence of 5 randomly choosen numbers from a list:

(iter-do (item (random-generators-sequence-from '(2 4 6 8) 5)) (message (format "item is %d" item)))

Note random-generators-sequence-from-or-empty can be used if instead of non-empty sequence like '(2 4 6 8) you pass possibly empty one as in this case no error will be thown for '(). The same rule applies to random-generators-list-from function too.

FAQ

• Why provided functions are more predictable than standard ones? Because they explicitly mandate user to pass just integer arguments for range borders and unlike random don't generate unconstrained random numbers with LIMIT < 0 which can be unexpected behavior.
• Why to use generators to generate random sequences? As long as sequences can be extremely long not to consume too much memory it's better to use generators.