In its simplest form, Guile acts as an interactive interpreter for the
Scheme programming language, reading and evaluating Scheme expressions
the user enters from the terminal. Here is a sample interaction between
Guile and a user; the user’s input appears after the $ and
scheme@(guile-user)> prompts:
$ guile
scheme@(guile-user)> (+ 1 2 3) ; add some numbers
$1 = 6
scheme@(guile-user)> (define (factorial n) ; define a function
(if (zero? n) 1 (* n (factorial (- n 1)))))
scheme@(guile-user)> (factorial 20)
$2 = 2432902008176640000
scheme@(guile-user)> (getpwnam "root") ; look in /etc/passwd
$3 = #("root" "x" 0 0 "root" "/root" "/bin/bash")
scheme@(guile-user)> C-d
$