clisp-interpreter, Kellie Dinh

A Common Lisp interpreter written in JavaScript

How to run

Once in the clisp-interpreter folder, run node repl.js

If node is not installed, it can be installed via Homebrew brew install node.

Testing suite is up-to-date: run npm run test

Quit using (quit) or (QUIT)

What it does

In depth paper included as Senior_Project.pdf

Updated 4/19/19

• Loading a file

  • (load 'lisp-file.lisp) loads in a file called 'lisp-file.lisp' however the extension doesn't matter for this program, as long as the filename is prefixed with a quote symbol

• Defining new functions

  • Can only be on one line i.e. (defun averageNum (n1 n2 n3 n4) (/ (+ n1 n2 n3 n4) 4))
  • Calling a user-defined function binds the local variable name with that value
    • (averageNum 1 2 3 4) binds parameters n1 to 1, n2 to 2, n3 to 3, n4 to 4

• Setting new global variables using setq

  • (setq a 1 b 2 c 3) sets a to 1, b to 2, c to 3
  • (setq a 3) updates the value of a to 3

• List operators cdr and cons

  • (car (cdr (cdr '(a b c d))))

• Better and more informative error messages that don't crash the program

End update

• Evaluation of number atoms

  • 5, +5, -5

• Basic calculations involving addition, subtraction, multiplication, and integer divison.

• Able to handle multiple arguments to +, -, *

  • (+ 1 2 3)
  • (- 3 2 1)
  • (* 3 3 3)

• Integer division handles only two arguements.

  • (/ 6 3)

• Nested expressions

  • addition (+ 3 (+ 2 9)) = 11
  • multiple operators (+ 8 (* 3 3)) = 17
  • more than two arguments to a nested expression
    • (+ 5 (+ 2 3 4)) = 14
    • (/ 8 (* 1 2 1)) = 4
    • (+ (- 5 4) (+ 1 3)) = 5

• Truth evaluations: > , <, >=, <=,$ =, equal, /=

• Quote, null, nil

• Basic list operators: listp, cons, list

  • (list (+ 3 2) 4 9) = (5 4 9)

• If statements:

  • (if (< 3 4) (+ 1 2) (/ 5 8)) = 3
  • (if (< (+ 3 4) (- 20 4)) (3) (4)) = 3

• Global variables

  • (setq x 5)
  • (+ 1 x) /* should print 6 */

More examples are included in my testing suite in the file klisp.test.js

Error Handling

Implemented as a Node module defined in the file error.js

Custom-defined errors that print messages but do not end the program

Not implemented

• Parenthesis matching
• Allow user to continue input if they leave off a closing parenthesis
• Local variables - let, do, function, progn, lambdas
• Can not handle recursion - our-member test function infinitely runs.
• Double quotes do not work