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https://lips.js.orgA Scheme interpreter implemented in JavaScript. The documentation covers core language features including S-expressions, Lisp macros, continuations, and streams, as well as LIPS-specific features like SXML, environment chains, and integration with the browser and GNU Emacs. It includes a comprehensive function and macro reference, SRFI support, and details on version 1.0.0-beta releases.
null. If no rules match while in a non-null state, characters are collected into the current token. This approach allows for dynamic syntax extensions and is used for both reading LIPS Scheme code and I/O ports.The Web REPL provides an interactive session for LIPS Scheme accessible via the home page or as a bookmarklet. It is built using jQuery Terminal and includes the following developer features:
// LIPS Procedures for inspection
(dir object) // Returns all accessible properties, including those from the prototype chain
(env) // Returns everything inside the current environment
// Standard JavaScript methods
Object.keys(obj) // Returns all string keys
Object.values(obj) // Returns the values of the object
Object.entries(obj) // Returns [key, value] pairs
Object.getOwnPropertySymbols(obj) // Returns all symbol propertieslet-env macro evaluates the provided body within the context of a given environment object. let-env-values adds specific variable mappings from an environment while maintaining lexical scope.(let-env env body)
(let-env-values env ((name var)) body)toString lambda. Additionally, the add-repr! function can be used to add string representations to objects.map (returns a new list) and for-each (returns an unspecified value).;; Using built-in map
(map square '(1 2 3 4)) ;; ==> (1 4 9 16)
(map (lambda (x) (* x 10)) '(1 2 3 4)) ;; ==> (10 20 30 40)
;; Defining a custom filter function
(define (filter fn lst)
(if (null? lst)
'()
(let ((item (car lst)))
(if (fn item)
(cons item (filter fn (cdr lst)))
(filter fn (cdr lst))))))
(filter odd? '(1 2 3 4 5)) ;; ==> (1 3 5)current-input-port points to the parser stream. This allows you to implement custom parser logic similar to Common Lisp reader macros by using functions like peek-char and read-char to consume the input stream manually.(define (raw-string)
(if (char=? (peek-char) #")
(begin
(read-char)
(let loop ((result (vector)) (char (peek-char)))
(read-char)
(if (char=? char #")
(apply string (vector->list result))
(loop (vector-append result (vector char)) (peek-char)))))))
(set-special! "$" raw-string lips.specials.SYMBOL)
(print $:"foo \ bar")
;; ==> "foo \\ bar"Because dedicated books on Scheme hygienic macros are scarce, the following documents and guides are recommended for learning syntax-rules and hygienic macro systems: