REBOL, aka Relative Expression-Based Object Language, is an open source programming language created in 1997 by Carl Sassenrath.
|#158on PLDB||26Years Old||30kRepos|
REBOL [Title: "Main"] print "Hello, world!"
print "Hello World"
; Hello World in REBOL print "Hello World!"
Rebol  hello: func  [ print "hello, world!" ] hello
Digit: charset [#"0" - #"9"] Value: [some Digit | "(" Expr ")"] Product: [Value any [["*"| "/"] Value]] Sum: [Product any [["+"| "-"] Product]] Expr: Sum parse/all "12+13" Expr