#!/usr/bin/env newlisp

(context 'Type)
(constant 'escape "\027[")

(set 'cls (string escape "2J"))
(set 'column-zero (string escape ";0H"))
(set 'move-away (string escape "25;25H"))
(set 'typing-speed 100) 
(set 'reading-pause 1500)

(define (display chars)
  (println column-zero chars move-away))

(define (Type:Type str)
  (println cls)
  (for (i 0 (length str))
      (display (string (0 i str)))
      (if (< (char (str (- i 1))) 32) 
         (sleep reading-pause) 
         (sleep typing-speed))) "")

(Type [text]; A typewriter effect for ANSI (VT100) terminals.
; First, we create a context for our stuff
; to avoid a lecture from the Scope Police
(context 'Type)
(constant 'escape "\027[")
; that's an ANSI escape signal. Make it a constant, it's not going to change.
(set 'cls (string escape "2J"))
; That will clear the screen.
(set 'column-zero (string escape ";0H"))
; and that will send the cursor back to the beginning of the line.
(set 'move-away (string escape "25;25H"))
; That just sends the cursor somewhere else!
(set 'typing-speed 100)
; How fast can you type? This is milliseconds.
(set 'reading-pause 2000)
; And how fast can you read each line?
(define (display chars)
  (println column-zero chars move-away))
; that will print the characters and then move the cursor away.
; The context's default function sends the lines to (display).
; In slices.
(define (Type:Type str)
  (println cls)
  (for (i 0 (length str))
      (display (string (0 i str)))
      ; that's a slice from the beginning to i
      (if (< (char (str (- i 1))) 32)
         ; cr/lf - time for a short break
         (sleep reading-pause) 
         ; how fast is that typing?
         (sleep typing-speed))) "")
; To run:
(Type "text")
>
[/text])