jar2.hin

来自「1984-1993模糊 C 源代码竞赛.zip 非常的好,不过这是DOS格式,」· HIN 代码 · 共 66 行

Best of show: <...!uunet!mcvax!hutcs!jar> Jari Arkko, Ora Lassila, Esko Nuutila

	Jari Arkko, Ora Lassila, Esko Nuutila
	Laboratory of Information Processing Science
	Helsinki University of Technology
	Otakaari 1
	02150 Espoo
	Finland

Judges notes:

	This is the most useful program entered this year. It is a
	rather large subset of lisp.  It has no error recovery, and
	performs rather poorly in a number of cases.  Even so, placing
	all this functionality in such a small, densely packed program,
	is impressive enough to win the Best of show award.

Selected notes from the author:

	This program implements a Lisp interpreter in 1465 bytes of source.
	Some sophisticated features supported, eg. functionals and recursion.  
	The special-forms/functions/variables implemented are:
	
		+	-	*	<	()	
		car	cdr	cons	defun	equal
		function if	lambda	quote	t
	
	Below are sample lisp expressions you might choose to try as input.
	The program implements a conventional lisp listener, i.e. you type in
	lisp expressions (followed by CR), the program evaluates them and
	prints out the return values. End execution by typing an end-of-file
	character.
	
	(+ 2.5 3.1)
	(defun fib (n)
	   (if (< n 2)
	       1
	       (+ (fib (- n 2)) (fib (- n 1)))))
	(fib 10)
	(defun ! (x) (if (equal x 0) 1 (* x (! (- x 1)))))
	(! 7)
	(defun fn1 (fn) (+ (fn 1 2) (fn 3 4)))
	(defun fn2 (a b) (+ a b))
	(fn1 (function +))
	(fn1 (function fn2))
	(fn1 (function (lambda (z1 z2) (+ z1 z2))))
	(quote a)
	(cons (quote (a b)) (quote (c d e)))
	(cons (quote (f)) ())
	(car (quote (a b c)))
	(cdr (cdr (quote (g h i))))
	
	Please do not leave any whitespace before the first parenthesis when
	you type your input, or any other unnecessary whitespace. Please try to
	avoid any undefined variables or functions, wrong number of arguments
	etc. All these errors are likely to dump core (i.e. there are no error
	checks in the program).
	
	Traditional Lisp implementations use cons cells as the main data
	structure. Lists are organized of pointer chains of these cells.
	In this program, an alternate representation was chosen: char*'s.
	All list operations, including the ones in the interpreter, are
	made using string representations of the lists. These operations
	must count parentheses and skip whitespace. This leads to extremely
	poor performance!