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MOROS Lisp

A minimalist Lisp interpreter is available in MOROS to extend the capabilities of the Shell.

MOROS Lisp is a Lisp-1 dialect inspired by Scheme and Clojure.

It started from Risp and was extended to include the seven primitive operators and the two special forms of John McCarthy's paper "Recursive Functions of Symbolic Expressions and Their Computation by Machine" (1960) and "The Roots of Lisp" (2002) by Paul Graham.

In version 0.2.0 the whole implementation was refactored and the parser was rewritten to use Nom. This allowed the addition of strings to the language and reading from the filesystem.

Seven Primitive Operators

  • quote (with the ' syntax)
  • atom (aliased to atom?)
  • eq (aliased to eq?)
  • car (aliased to first)
  • cdr (aliased to rest)
  • cons
  • cond

Two Special Forms

  • label (aliased to def)
  • lambda (aliased to fn)

Additional Builtins

  • defun (aliased to defn)

  • mapcar (aliased to map)

  • print

  • read

  • read-bytes

  • bytes

  • str

  • cat

  • join

  • lines

  • parse

  • type

  • system

  • Arithmetic operations: +, -, *, /, %, ^

  • Trigonometric functions: acos, asin, atan, cos, sin, tan

  • Comparisons: >, <, >=, <=, =

  • Boolean operations: and, or

Usage

The interpreter can be invoked from the shell:

> lisp
MOROS Lisp v0.1.0

> (+ 1 2)
3

> (quit)

And it can execute a file. For example a file located in /tmp/fibonacci.lsp with the following content:

(defn fib (n)
  (cond
    ((< n 2) n)
    (true (+ (fib (- n 1)) (fib (- n 2))))))

(println (fib 10))

Would produce the following output:

> lisp /tmp/fibonacci.lsp
55