lambdaway :: lambdacode

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_img http://lambdaway.free.fr/workshop/data/mies_pav.jpg

_h1 lambdacode {sup ( 1 | [[2|?view=lambdacode2]] | [[3|?view=lambdacode3]] | [[4|?view=lambdacode4]] | [[5|?view=lambdacode5]]) }

_p Everything in the {b LISP} world began with the initial code of John McCarthy on which worked a lot of good people, Abelson & Sussman, Paul Graham, and several others. {b Peter Norvig} wrote a smart and well documented LISP interpreter in the PYTHON language, [[lispy|http://norvig.com/lispy.html]]. A few young coders, {b Sreedathns, Sainamdar} and others, proposed their own translations in Javascript which inspired me greatly. {b (lambda code)} is my (last) translation of the Peter Norvig's LISP engine, replacing pairs and lists by arrays and adding strings and HTML/CSS capabilities.
 
_p This is a standard {b AST} evaluator, {b tokenizing} the input string, building an {b abstract syntaxic tree} and {b parsing} it, whose kernel is built in less than 100 JS lines. A first set of primitives is given for HTML/CSS/SVG/JS and a small linrary on big numbers.

_p Just write in the wiki page

{pre 
'{AST 
... any valid code ...
}
}

_p to get its evaluation done in real time. Currently this is a first example:

{AST
(@ 1. evaluation)
'
'(div (@ style="font:italic 3.0em papyrus")
    (@ hello world))
'
(div (@ style="font:italic 3.0em papyrus")
    (@ hello world))
'(sqrt (+ (* 3 3) (* 4 4)))
(sqrt (+ (* 3 3) (* 4 4))) 
'
(@ 2. IIFE: Immediately Invoked Function Expression)
'
'((lambda (x y)
 (sqrt (+ (* x x) (* y y))))
  3 4)
((lambda (x y) (sqrt (+ (* x x) (* y y)))) 3 4) 
'
(@ 3. abstraction and application)
'
'(def hypo
 (lambda (x y)
  (sqrt (+ (* x x) (* y y)))))
(def hypo
 (lambda (x y)
  (sqrt (+ (* x x) (* y y)))))
'
'(hypo 3 4)
(hypo 3 4)
'
'(hypo 1 1)
(hypo 1 1)
'
(@ 4. quoting)
'
''hello
'hello
'
'(@ hello world)
(@ hello world)
'
'(join '1+2 '= (+ 1 2))
(join '1+2 '= (+ 1 2))
'
(@ 5. closure)
'
'(def closure
 (lambda (a)
  (lambda (b)
   (* a b))))
(def closure
 (lambda (a)
  (lambda (b)
   (* a b))))
'
'((closure 3) 4)
((closure 3) 4)
'
'(def triangle
 (lambda (a b c)
  ((lambda (s)
   (sqrt (* s (- s a) (- s b) (- s c)))
   ) (/ (+ a b c) 2))
))
(def triangle
 (lambda (a b c)
  ((lambda (s)
   (sqrt (* s (- s a) (- s b) (- s c)))) (/ (+ a b c) 2))))
'
'(triangle 3 4 5) 
(triangle 3 4 5)
'
(@ 6. recursion)
'
(def fac
 (lambda (n)
  (if (< n 1)
   1
   (* n (fac (- n 1))))))
'(def fac
 (lambda (n)
  (if (< n 1)
   1
   (* n (fac (- n 1))))))
'
'(fac 100)
(fac 100)
'
'(FAC 100)
(FAC 100)
'
'(lib)
(lib)
}

_h2 notes
_ul 1) During the tokenization line returns are broken leading to a bad display of these code

{prewrap
(def fac (lambda (n) (if (< n 1) 1 (* n (fac (- n 1))))))

(def triangle (lambda (a b c) ((lambda (s) (sqrt (* s (- s a) (- s b) (- s c)))) (/ (+ a b c) 2)))) 
}

_p These code should be displayed like this

{pre
(def fac
 (lambda (n)
  (if (< n 1)
   1
   (* n (fac (- n 1))))))

(def triangle
 (lambda (a b c)
  ((lambda (s)
   (sqrt (* s (- s a) (- s b) (- s c)))) 
    (/ (+ a b c) 2)))) 
}

_ul 2) ...

_p Any help is welcome.

_h2 other examples

_p The following examples can be copied and pasted in the AST container.

{pre
(@ 1. evaluation)
(sqrt (+ (* 3 3) (* 4 4))) 
'
(@ 2. IIFE: Immediately Invoked Function Expression)
((lambda (x y) (sqrt (+ (* x x) (* y y)))) 3 4)
'
(@ 3. abstraction)
(def hypo
 (lambda (x y)
  (sqrt (+ (* x x) (* y y)))))
'
(@ 4. application)
(hypo 3 4)
(hypo 1 1)
'
(@ 5. protection)
'hello
(@ hello world)
(@ hello (+ 1 2))
(join 'hello (+ 1 2))

'
(@ 6. primitives)
(lib)

=========

A) first tests

'hello 'world

(@ hello world)

(+ 1 (* 2 3) 4)

(sqrt (+ (* 3 3) (* 4 4)))

(def hypo
 (lambda (x y)
  (sqrt (+ (* x x) (* y y)))))

(hypo 3 4)
(hypo 1 1)

(def triangle
 (lambda (:a :b :c)
  ((lambda (:s)
   (sqrt (* :s (- :s :a) (- :s :b) (- :s :c)))
   ) (/ (+ :a :b :c) 2))
))

(triangle 3 4 5)

(def fac
 (lambda (n)
  (if (< n 1)
   1
   (* n (fac (- n 1))))))
(fac 100)

(def closure
 (lambda (a)
  (lambda (b)
   (* a b))))

(closure 3)
((closure 3) 4)

B) booleans, pairs, lists & recursion exclusively built on lambdas

(def TRUE (lambda (x y) x))
(def FALSE (lambda (x y) y))
(def IF (lambda (x y z) (x y z)))

(def PAIR (lambda (x y) (lambda (z) (z x y))))
(def LEFT (lambda (z) (z TRUE)))
(def RIGHT (lambda (z) (z FALSE)))
(def NIL (lambda (s z) z))
(def ISNIL (lambda (n) (n (lambda (x) FALSE) TRUE)))
'---
(def DISP
 (lambda (list)
  ((IF (ISNIL list)
    (lambda (list) '.)
    (lambda (list) (join (LEFT list) (DISP (RIGHT list)) ))
   ) list)))
'---
(def FRUITS
 (PAIR 'apple
  (PAIR 'banana
   (PAIR 'lemon
    (PAIR 'grapes
     (PAIR 'orange NIL))))))

(DISP FRUITS)

C) arrays for everything

(def A (#.new 1 2 3 4 5))
A
(#.length A)

(def map
 (lambda (f x y)
  (if (#.empty? x)
   y
   (map f (#.rest x) (#.push! y (f (#.first x)))))))

(map (lambda(x) (* x x)) A (#.new))

...

D) HTML/CSS

(center (@ hello world))

(div (@ style="font-size:3.0em;") (@ hello world))
 
(img (@ src="data/amelie_poulain.jpg" width="100px") '.)

(p (a (@ href="http://www.pixar.com") 'PIXAR))

(svg
 (@ width="100%" height="200px" style="background:#eee;")
 (join
  (polyline 
   (@ points="10 10 100 190 100 10 580 10" 
      stroke-width="1" stroke="#888" fill="transparent") '.) 
  (path 
   (@ d="M 10 10 C 100 190 100 10 580 10"  
      stroke-width="3" stroke="#f00" fill="transparent") '.)
))
 
}

_h2 javscript code

_h3 1) the function AST

{pre
°°

LAMBDATALK.DICT['AST'] = function() {
  var cod = arguments[0];
  var val = LC.parser( cod );
  var infos = '(' + val.bal[0] + '|' + val.bal[1] + ') ' 
            + val.time + ' ms';
  var evaluation = ( val.bal[0] !== val.bal[1] ) ? cod : val.val;
  return '< center>' + infos + '< /center>' + 
         '< pre>' + evaluation + '< /pre>'
};
°°}

_h3 2) the kernel

{pre °°
var LC = (function () {

var DICT = create_env([],[]);

var tokenize = function ( s ) { 
  return s.replace(/$/g, ' ( ')
          .replace(/$/g, ' ) ')
          .trim().split(/\s+/);        
};

var build_tree = function (tokens) {
  var token = tokens.shift();
  if (token !== '(') 
    return token;
  var arr = [];
  while (tokens[0] !== ')')
    arr.push( build_tree(tokens) );
  tokens.shift();
  return arr;
};

var isNumber = function (x) {
  return !isNaN(parseFloat(x)) && isFinite(x)
};

var isWord = function (x) {
  return typeof x === 'string' && x.charAt(0) === '\''
};

var isOp = function (x) {  
  return typeof x === 'string'
};

var array2string = function(x) {
  return JSON.stringify( x ).replace( /\[/g, '(' )
                            .replace( /\]/g, ')' )
                            .replace( /"/g,   '' )
                            .replace( /,/g,  ' ' )
};

var pre_processing = function( str ) {
  str = str.replace( /'\(/g, "(quote " );
  return str
};

return { parser, DICT }

}());
°°}

_h3 3) populating the dictionary

{prewrap °°

LC.DICT['lib'] = function() {
  var str = '', index = 0;
  for (var key in LC.DICT) {
    if(LC.DICT.hasOwnProperty(key)) { 
      str += key + ', '; index++; 
    }
  }
  return '<b>DICT: </b>('+ index+') [ '+ str.substring(0,str.length-2)+' ]<br />';
};
LC.DICT['console'] = function(){
  return [].slice.call(arguments).join('\n')
}; 
LC.DICT['join'] = function() {
  return [].slice.call(arguments).join(' ')
};

LC.DICT['+'] = function () {
  for (var r=0, i=0; i < arguments.length; i++) { 
    r += Number( arguments[i] ) 
  }
  return r; 
};
LC.DICT['*'] = function () {
  for (var r=1, i=0; i < arguments.length; i++) { 
    r *= arguments[i] 
  }
  return r;  
};
LC.DICT['-'] = function () {
  var r = arguments[0];
  if (arguments.length === 1) { 
    r = -r;
  } else { 
    for (var i=1; i < arguments.length; i++) { 
      r -= arguments[i] 
    } 
  }
  return r; 
};
LC.DICT['/'] = function () {
  var r = arguments[0];
  if (arguments.length === 1) {
    r = 1/r;
  } else { 
    for (var i=1; i < arguments.length; i++) { 
      r /= arguments[i] 
    } 
  }
  return r; 
};
LC.DICT['%'] = function () {
  return parseFloat(arguments[0]) % parseFloat(arguments[1]) 
};

LC.DICT['<']  = function(){
  return parseFloat(arguments[0]) < parseFloat(arguments[1]) 
};
LC.DICT['>']  = function(){
  return parseFloat(arguments[0]) > parseFloat(arguments[1]) 
};
LC.DICT['<=']  = function(){  
  return parseFloat(arguments[0]) <= parseFloat(arguments[1]) 
};

LC.DICT['>=']  = function(){
  return parseFloat(arguments[0]) >= parseFloat(arguments[1]) 
};
LC.DICT['=']  = function () {
  var a = parseFloat(arguments[0]), b = parseFloat(arguments[1]);  
  return !(a < b) && !(b < a) 
};
LC.DICT['not'] = function () {
return !arguments[0]
};
LC.DICT['or'] = function () { 
  for (var i=0; i< arguments.length; i++) { if (arguments[i]) return true }
  return false; 
};
LC.DICT['and'] = function () { 
  for (var i=0; i< arguments.length; i++) { if (arguments[i]) return false }
  return true; 
};
LC.DICT['equal?'] = function(a, b){ return a === b };

LC.DICT['#.new'] = function() {
  return [].slice.call(arguments)
};
LC.DICT['#.array?'] = function() {
  return Array.isArray( arguments[0] )
};
LC.DICT['#.disp'] = function() {
  var args = arguments[0];
  return ( Array.isArray( args ) )? JSON.stringify( args ) : args
};
LC.DICT['#.length'] = function() {
  return arguments[0].length
};
LC.DICT['#.empty?'] = function() {
  return arguments[0].length === 0
};
LC.DICT['#.first'] = function() {
  var args = arguments[0];
  return (Array.isArray( args ))? args[0] : args 
};
LC.DICT['#.last'] = function() {
  var args = arguments[0];
  return (Array.isArray( args ))? args[args.length-1] : args 
};
LC.DICT['#.rest'] = function() {
  var args = arguments[0];
  return (Array.isArray( args ))? args.slice(1) : args 
};
LC.DICT['#.get'] = function() {
  var val = arguments[0][arguments[1]];
  return (val !== undefined)? val : 'undefined'        
};
LC.DICT['#.slice'] = function() {
  return arguments[0].slice(arguments[1],arguments[2])
};
LC.DICT['#.concat'] = function() {
  return arguments[0].concat( arguments[1] )
};
LC.DICT['#.reverse'] = function() {
  return arguments[0].reverse()
};
LC.DICT['#.sort'] = function() {
  return (arguments[1] === 'up')? 
    arguments[0].sort( function(a,b) { return a - b } ) :
    arguments[0].sort( function(a,b) { return b - a } )
};
LC.DICT['#.set!'] = function() {
  arguments[0][arguments[1]] = arguments[2]
  return arguments[0]
};
LC.DICT['#.pop!'] = function() {
  return arguments[0].pop()
};
LC.DICT['#.shift!'] = function() {
  return arguments[0].shift()
};
LC.DICT['#.push!'] = function() {
  arguments[0].push( arguments[1] )
  return arguments[0];
};
LC.DICT['#.unshift!'] = function() {
  arguments[0].unshift( arguments[1] )
  return arguments[0];
};

°°}

{style 
body, #page_frame, #page_content, .page_menu, pre { background:#444; color:#fff; border:0 #444; box-shadow:0 0 0 #444; }
pre { box-shadow:0 0 8px #000; padding:10px; }
textarea {width:99%; height:1500px; background:#444; color:#fff; box-shadow:0 0 8px #000; border:0 #444; font:normal 1.0em courier; }
}

{script

LAMBDATALK.DICT['AST'] = function() {
  var cod = arguments[0];
  var val = LC.parser( cod );
  var infos = '(' + val.bal[0] + '|' + val.bal[1] + ') ' + val.time + ' ms';
  var evaluation = ( val.bal[0] !== val.bal[1] ) ? cod : val.val;
  return '<center>' + infos + '</center>' + 
         '<pre style="word-wrap:break-word; white-space:pre-wrap;">' + evaluation + '</pre>'
};

var LC = (function () {

var DICT = create_env([],[]);

return { parser, DICT }

}());

}

{script

var BI = (function() {

var N2A = function(n) {
  return n.toString().split('').reverse() 
};

var A2N = function(a) {
  return a.reverse().join('') 
};

return { N2A, A2N, ADD, MUL }
})();

LC.DICT['N2A'] = function() {
  return BI.N2A(arguments[0])
};
LC.DICT['A2N'] = function() {
  return BI.A2N(JSON.parse(arguments[0]))
};
LC.DICT['ADD'] = function() {
  return BI.A2N(BI.ADD(BI.N2A(arguments[0]),BI.N2A(arguments[1])))
};
LC.DICT['MUL'] = function() {
  return BI.A2N(BI.MUL(BI.N2A(arguments[0]),BI.N2A(arguments[1])))
};

LC.DICT['FAC'] = function() {
  var fac_r = function(a,b) {
    return (b < 1)? a : fac_r(BI.MUL(a, BI.N2A(b)), b-1)
  }; 
  return BI.A2N(fac_r( BI.N2A(1), parseInt(arguments[0]) ))
};

}