MLisp interpreter.

01

Start the REPL

Run mlisp without arguments to open the interactive read–evaluate–print loop.

$ mlisp
> (+ 20 22)
42
> (def name "MLisp")
"MLisp"
> (concat "Hello, " name)
"Hello, MLisp"

The same runtime is reused for every entry, so definitions remain available for the rest of the session. The primary prompt is >. When a form is not complete, the interpreter switches to .. and keeps reading lines until the expression closes.

> (let ((answer 42))
..   (print "answer:" answer))
answer: 42
nil

Send end-of-input to leave the REPL. An unfinished expression at that point is reported as an error.

02

Run a file

Pass one filename to read and evaluate that program, then exit. The filename may be an absolute path or a path relative to the current working directory.

; hello.mlisp
(def greeting "Hello from MLisp")
(print greeting)

$ mlisp hello.mlisp
Hello from MLisp
nil

The interpreter reads the file as UTF-8 and evaluates it as one input. Printed output appears first, followed by the value of the final form. A read or evaluation error names the file and exits with a failure status; earlier output and definitions are not rolled back.

03

Command summary

This guide intentionally starts small. Build and installation notes, platform details and additional runtime topics will be added as the interpreter develops.