Self-Hosted REPL

Because read-line, read-from-string, eval and print are available in every backend, a REPL can be written in RontoLisp itself and compiled to a standalone .class or .wasm:

Example (repl.lisp):

(princ "> ")
(setq line (read-line))
(while line
  (print (eval (read-from-string line)))
  (princ "> ")
  (setq line (read-line)))

rontolisp repl.lisp               # interpret
rontolisp repl.lisp -o repl.class
java repl                                                                  # REPL on the JVM
rontolisp repl.lisp -o repl.wasm
wasmtime run repl.wasm                                                     # REPL on WASM

The self-hosted REPL parses each input line with the embedded runtime reader (read-from-string), which upcases symbols like Common Lisp (see the reader case guide), so (defun square ...) echoes SQUARE, the same as the native REPL.

> (defun square (x) (* x x))
SQUARE
> (mapcar #'square '(1 2 3))
(1 4 9)
> ()
NIL
> (- 5)
-5

read-line returns nil only at end of input, so the loop exits on Ctrl-D. Entering nil or () evaluates to NIL and the loop keeps going, because the line is read with read-line (which distinguishes end of input from a datum) rather than reusing the read value as the loop's exit sentinel. Each line entered at the prompt is parsed by the runtime reader and evaluated by the embedded eval runtime, so the Compiled eval limitations and Compiled read/load limitations apply.