Forth - Programming language

Forth is a programming language created in 1970 by Charles H. Moore.

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Forth is an imperative stack-based computer programming language and environment originally designed by Charles "Chuck" Moore. Language features include structured programming, reflection (the ability to modify the program structure during program execution), concatenative programming (functions are composed with juxtaposition) and extensibility (the programmer can create new commands). Although not an acronym, the language's name is sometimes spelled with all capital letters as FORTH, following the customary usage during its earlier years. Read more on Wikipedia...

Forth Wikipedia page
Forth docs
There are at least 1,537 Forth repos on GitHub
Forth first developed in National Radio Astronomy Observatory
file extensions for Forth include fth, 4th, f, for, forth, fr, frt and fs
The Google BigQuery Public Dataset GitHub snapshot shows 2k users using Forth in 2k repos on GitHub
There are 63 Project Euler users using Forth
Explore Forth snippets on Rosetta Code
Forth on HOPL
Forth appears in the TIOBE Index
Forth Ubuntu package
CodeMirror package for syntax highlighting Forth
Pygments supports syntax highlighting for Forth
GitHub supports syntax highlighting for Forth
Forth appears in the Quine Relay project
PLDB has 2 Jupyter Kernels for Forth: github.com, github.com
There is a central package repository for Forth
Indeed.com has 0 matches for "forth developer".
See also: (15 related languages)Lisp, APL, Factor, PostScript, RPL, REBOL, Reverse Polish notation, FreeBSD, C, Linux, Unix, Atmel AVR, TI MSP430, ASCII, Joy

Example from Riju:

." Hello, world!" CR

Example from hello-world:

.( Hello World)

Example from the Hello World Collection:

' Hello world in Forth

." Hello World" CR

Example from Linguist:

: HELLO  ( -- )
    ." Hello Forth (fth)!" ; 

HELLO

Example from Wikipedia:

hex
create AKey   61 c, 8A c, 63 c, D2 c, FB c,
: test   cr   0 DO  rc4_byte . LOOP  cr ;
AKey 5 rc4_init
2C F9 4C EE DC  5 test   \ output should be: F1 38 29 C9 DE

Feature	Supported	Token	Example
Integers	✓		\ (\#\|%\|&\|\-\|\+)?[0-9]+
Hexadecimals	✓		\ (\$[0-9A-F]+)
Print() Debugging	✓	.
Line Comments	✓	\	\ A comment
Postfix Notation	✓		\ Multiplies 25 and 10 and then adds 50 to result 25 10 * 50 +
Case Insensitive Identifiers	✓
Comments	✓
Semantic Indentation	X
Case Sensitivity	X