Course-JavaScript/Slang/slang.js

/**********************************************************************
* 
*
*
**********************************************************************/

/* XXX for some odd reason this breaks the interpreter...
Array.prototype.toString = function(){
	return '[ ' + this.join(', ') + ' ]'
}
*/


/*********************************************************************/

function run(context){

	context.stack = context.stack == null ? [] : context.stack

	while(context.code.length > 0){

		var cur = context.code.splice(0, 1)[0]

		// exit...
		if(typeof(cur) == typeof('abc') && cur == '_exit'){
			return context

		// word
		} else if(typeof(cur) == typeof('abc') && cur in context.ns){
			var word = context.ns[cur]
			// low-level word...
			if(typeof(word) == typeof(function(){})){
				var res = context.ns[cur](context)

			// hi-level word...
			} else if(typeof(word) == typeof([]) && word && word.constructor.name == 'Array'){
				// XXX add isolation with a continuation...
				context.code.splice.apply(context.code, [0, 0].concat(word))
				var res = undefined

			// variable...
			} else {
				var res = word
			}

			if(res !== undefined){
				context.stack.push(res)
			}

		// everything else...
		} else {
			context.stack.push(cur)
		}
	}

	return context
}

// XXX make this add '\n' / EOL words to the stream...
//var SPLITTER = /\s*\([^\)]*\)\s*|\s*--.*[\n$]|\s*"([^"]*)"\s*|\s*'([^']*)'\s*|\s+/m
var SPLITTER = RegExp([
			/* XXX there are two ways to deal with comments:
			//			1) lexer-based -- this section commented, next uncommented...
			//			2) macro-based -- this section uncommented, next commented...
			//		#2 is a bit buggy...
			// terms to keep in the stream...
			'\\s*('+[
				'\\n',
				'--',
			].join('|')+')',
			//*/

			//* lexer comments...
			'\\s*\\([^\\)]*\\)\\s*',
			'\\s*--.*[\\n$]',
			//*/

			// quoted strings...
			'\\s*"([^"]*)"\\s*',
			"\\s*'([^']*)'\\s*",

			// quote...
			'\\s*(\\\\)',

			// whitespace...
			'\\s+',
		].join('|'),
		'm')


// helpers...
// XXX should these skip quoted ends?
var collect = function(start, end){
	return function(context){
		var res = start ? [start] : []
		var code = context.code
		var cur = code.shift()
		res.push(cur)
		while(cur != end && code.length > 0){
			cur = code.shift()
			res.push(cur)
		}
		return res
	}
}
var drop = function(start, end){
	var collector = collect(start, end)
	//return function(context){ collector(context) }
	return function(context){ console.log('XXX', collector(context).join(' ')) }
}


// pre-processor namespace...
var PRE_NAMESPACE = {
	// comment...
	// syntax: -- ... \n
	//
	// drop everything until '\n'
	//
	// NOTE: this depends on explicit '\n' words...
	//'--': drop('--', '\n'),
	'(': drop('(', ')'),
	
	// XXX use the real reader...
	// block...
	// syntax: [ ... ]
	// NOTE: the shorthand ']]' will close ALL the open blocks.
	// XXX should ']]' be smart enough to look ahead and close only the 
	// 		blocks not explicitly closed later???
	// 		..see below for more...
	'[': function(context){
		var block = []
		var code = context.code
		var cur = code.splice(0, 1)[0]
		while(cur != ']' && cur != ']]' && code.length > 0){
			if(cur == '['){
				cur = this['['](context)
			}
			block.push(cur)
			cur = code.splice(0, 1)[0]
		}
		// we need this to be able to jump out of all the nested blocks, 
		// thus we'll keep the ']]' in code and remove it explicitly 
		// later...
		if(cur == ']]'){
			// XXX should we look ahead and count the explicitly closed
			// 		via ']' and ']]' blocks???
			// 		...at this point this seems a bit complex...
			// 		...if there are more than one ']]' in a structure
			//		this might stop being deterministic...
			code.splice(0, 0, cur)
		}
		if(code.length == 0 && cur != ']' && cur != ']]'){
			console.error('Did not find expected "]".')
		} 
		return block
	},
	// drop the closing words...
	']]': function(context){},
	']': function(context){ console.error('Unexpected "]".') },

	// XXX macros are not recursive...
	'macro:': function(context){
		var ident = context.code.splice(0, 1)
		var cur = context.code.splice(0, 1)

		// as we do not have blocks yet we need to manually collect one ;)
		if(cur[0] == '['){
			cur = [ this['['](context) ]
		}

		this[ident] = cur[0]
	},

	// a no op...
	'\n': function(){ },
}


// main namespace...
var NAMESPACE = {
	// constants...
	'true': true,
	'false': false,
	'null': 'null',

	'nop': function(){}, 

	'is?': function(context){ 
		return context.stack.pop() === context.stack.pop() },

	// XXX experimental...
	// flip the code and stack...
	// ... -- ...
	'_flip': function(context){
		var stack = context.stack
		context.stack = context.code.reverse()
		context.code = stack.reverse()
	},

	// swap heads of stack and code
	// ... ns nc -- ...
	'_swapN': function(context){ 
		var c = context.stack.pop()
		var s = context.stack.pop()
		var l = context.stack.length

		// get the stack/code sections to swap...
		var s_c = context.stack.splice(l-s, l)
		var c_c = context.code.splice(0, c)
		var l = context.stack.length

		// we need to pad e_c and c_c to requested length...
		s_c = s_c.length < s ? s_c.concat(Array( s - s_c.length )) : s_c
		c_c = c_c.length < c ? c_c.concat(Array( c - c_c.length )) : c_c

		// XXX we also need to shove something more sensible in the 
		// 		padding that undefined...

		context.code.splice.apply(context.code, [0, 0].concat(s_c))
		context.stack.splice.apply(context.stack, [l, 0].concat(c_c))
	},

	// encapsulate stack to a block...
	// ... -- [ ... ]
	's2b': function(context){
		context.stack = [ context.stack ] },
	// expand block to stack... 
	// NOTE: this will append the block contents to stack, w.o. replacing 
	// 		stack contents. this is different to _s2b
	// ... [ ... ] -- ... ...
	'b2s': function(context){
		var c = context.stack.pop()
		c = c === undefined ? [] : c
		context.stack.splice.apply(context.stack, [context.stack.length, 0].concat(c))
	},
	'print': function(context){
		console.log('>>>', context.stack[context.stack.length-1]) },

	// turn a sting into a lexical list...
	// c -- b
	// XXX BUG see code...
	'lex': function(context){
		code = context.stack.pop()
		if(typeof(code) == typeof('abc')){
			// XXX BUG: '"aaa" "bbb"' translates to ['"aaa"', '" "', '"bbb"'] 
			// 		i.e. quotes w/o whitespace are eaten...
			if(/^\s*(['"]).*\1\s*$/m.test(code)){
				code = code.split(/^\s*(['"])(.*)\1\s*$/m)[2]
			}

			//console.log(code)

			var res = []
			code = code
				// split by strings whitespace and block comments...
				.split(SPLITTER)
				// parse numbers...
				.map(function(e){ 
					// numbers...
					if(/^[-+]?[0-9]+\.[0-9]+$/.test(e)){
						e = parseFloat(e)
					} else if(/^[-+]?[0-9]+$/.test(e)){
						e = parseInt(e)
					}
					return e
				})
				// remove undefined groups...
				.filter(function(e){ 
					// NOTE: in JS 0 == '' is true ;)
					return e !== undefined && e !== ''
				})
		}
		return code
	},
	// pre-process a lexical list...
	// a -- b
	'prep': function(context){
		var code = context.stack.pop()

		return run({
			stack: [],
			code: code,
			ns: context.pre_ns,
			pre_ns: {},
		}).stack
	},

	// s c -- s
	'_exec': function(context){
		// block...
		var b = context.stack.pop()
		if(typeof(b) == typeof([]) && b && b.constructor.name == 'Array'){
			b = b.slice()
		} else {
			b = [ b ]
		}
		// stack...
		var s = context.stack.pop()
		var res = run({
			stack: s,
			code: b,
			// NOTE: this can have side-effects on the context...
			ns: context.ns,
			pre_ns: context.pre_ns
		})
		// XXX is this the right way to go?
		context.ns = res.ns
		context.pre_ns = res.pre_ns
		return res.stack
	},
	// quote - push the next elem as-is to stack...
	// -- x
	'\\': function(context){
		return context.code.splice(0, 1)[0] },

	// comparisons and logic...
	// a b -- c
	'and': function(context){
		var b = context.stack.pop()
		var a = context.stack.pop()
		if(a){
			return b
		} else {
			return a
		}
	},
	// a b -- c
	'or': function(context){
		var b = context.stack.pop()
		var a = context.stack.pop()
		if(a){
			return a
		} else {
			return b
		}
	},
	// x -- b
	'not': function(context){
		return !context.stack.pop() },
	// a b -- c
	'gt': function(context){
		return context.stack.pop() < context.stack.pop() },
	// a b -- c
	'eq': function(context){
		return context.stack.pop() == context.stack.pop() },

	// stack operations...
	// ... x -- x ...
	'rot': function(context){
		context.stack.splice(0, 0, context.stack.pop()) },
	// x ... -- ... x
	'tor': function(context){
		context.stack.push(context.stack.shift()) },
	// a b -- b a
	'swap': function(context){
		return context.stack.splice(context.stack.length-2, 1)[0] },
	// x -- x x
	'dup': function(context){
		return context.stack[context.stack.length-1] },
	// x -- x'
	// NOTE: this will do a deep copy...
	'clone': function(context){
		return JSON.parse(JSON.stringify(context.stack.pop())) },
	// x --
	'drop': function(context){
		context.stack.pop() },

	// a -- b
	// NOTE: all names are also strings so moo string? and 'moo' string?
	// 		are the same...
	'string?': function(context){
		return typeof(context.stack.pop()) == typeof('str') },

	// basic number operations...
	// a -- b
	'number?': function(context){
		return typeof(context.stack.pop()) == typeof(123) },
	// a b -- c
	'add': function(context){
		return context.stack.pop() + context.stack.pop() },
	'sub': function(context){
		return - context.stack.pop() + context.stack.pop() },
	'mul': function(context){
		return context.stack.pop() * context.stack.pop() },
	'div': function(context){
		return 1/context.stack.pop() * context.stack.pop() },

	// block/list operations...
	'block?': function(context){
		var e = context.stack.pop()
		return typeof(e) == typeof([]) && e && e.constructor.name == 'Array'
	},
	// b n -- b e
	'at': function(context){
		var i = context.stack.pop()
		if(i < 0){
			var l = context.stack[context.stack.length-1]
			return l[l.length + i]
		}
		return context.stack[context.stack.length-1][i]
	},
	// b e n -- b
	'to': function(context){
		var i = context.stack.pop()
		var e = context.stack.pop()
		if(i < 0){
			var l = context.stack[context.stack.length-1]
			l[l.length + i] = e
		} else {
			context.stack[context.stack.length-1][i] = e
		}
	},
	// b e n -- b
	'before': function(context){
		var i = context.stack.pop()
		var e = context.stack.pop()
		if(i < 0){
			var l = context.stack[context.stack.length-1]
			l.splice(l.length + i, 0, e)
		} else {
			context.stack[context.stack.length-1].splice(i, 0, e)
		}
	},
	// b -- b e
	'pop': function(context){
		return context.stack[context.stack.length-1].pop() },
	// b -- b l
	'len': function(context){
		return context.stack[context.stack.length-1].length },
	// b c -- b
	'map': function(context){
		var c = context.stack.pop()
		var b = context.stack[context.stack.length-1]
		for(var i=0; i < b.length; i++){
			// exec block in a separate context...
			var res = run({
				//stack: [b, i, b[i], c],
				stack: [b[i], c],
				code: ['exec'],
				// NOTE: this can have side-effects on the context...
				ns: context.ns
			}).stack
			var l = res.length
			if(l == 0){
				b.splice(i, 1)
				i--
			} else {
				b.splice.apply(b, [i, 1].concat(res))
				i += l - 1
			}
		}
	},


	// object stuff...
	'{}': function(){ return {} }, 

	'object?': function(context){
		var o = context.stack[context.stack.length - 1]
		return o && o.constructor === Object
	},

	// set item...
	// o k v -- o
	'item!': function(context){ 
		var v = context.stack.pop()
		var k = context.stack.pop()
		var o = context.stack[context.stack.length - 1]

		o[k] = v
   	},

	// test item...
	// o k -- o t
	'item?': function(context){ 
		return context.stack.pop() in context.stack[context.stack.length - 1] },

	// get item...
	// o k -- o v
	'item': function(context){ 
		var k = context.stack.pop()
		return context.stack[context.stack.length - 1][k] },

	// remove/pop item from object...
	// o k -- o v
	'popitem': function(context){ 
		var k = context.stack.pop()
		var o = context.stack[context.stack.length - 1]
		
		var v = o[k]
		delete o[k]

		return v
   	},

	// o -- k
	'keys': function(context){ 
		return Object.keys(context.stack.pop()) },

	// make a prototype of b...
	// a b -- b
	// NOTE: if a is false, reset prototype...
	'proto!': function(context){
		var b = context.stack.pop()
		var a = context.stack.pop()
		b.__proto__ = a === false ? {}.__proto__ : a
		return b
	},

	// o -- p
	// XXX what should this be:
	// 		{} getproto
	'proto': function(context){ 
		return context.stack.pop().__proto__ },

	// -- o
	'ns': function(context){ 
		return context.ns },
	// o --
	'ns!': function(context){ 
		context.ns = context.stack.pop() },
}


// NOTE: hate how JS handles multi-line strings...
var BOOTSTRAP =
`-------------------------------------------------------------------------------

 [S]lang is a [s]imple and complete [S]tack [lang]uage.

 Slang was designed for three main reasons:
	- a means to experiment with several aspects of language design,
	- an educational tool, to illustrate several programming language
	  concepts in a simple, hands-on manner,
	- fun!



-------------------------------------------------------------------------------

 Slang Basics
 ------------

 The system consists of:
	- Stack
	- Code
	- Namespace
	- basic runtime

 	                 { NAMESPACE }
	                       ^
	                       |
 	[ .. STACK .. ] <-- runtime -- [ .. CODE .. ]


 A namespace is a basic key/value store.

 The runtime "reads" entities from the code stream one by one and depending on
 whether an entity exists in the namespace it is either pushed on the stack
 or evaluated.

 The evaluated entity is traditionally called a "word" (function in non-stack
 languages). The only thing that makes a word different from any other entity
 is that it matches a key in the namespace, as mentioned above.

 In Slang evaluation is done simply by executing the value of the matched
 key/value pair in the namespace. An over-simplified way to explain
 evaluation is to say that the content of the value is pushed to the
 code stream to be read right away, that\'s almost it, if we skip a
 couple of details (see: _exec, exec and for details see: eval)

 The system contains two types of words:
	- Host words -- defined by the host system,
	- User words -- defined within the system (like this bootstrap code).

 Words may read and affect any of the three system parts:
	- Stack
	- Code
	- Namespace

 Traditioannly, in stack languages words affect only the stack, this is
 one of the motivations to implement Slang, that is, to experiment with
 different ways to go with stack languages.


 TODO: add topological comparison/diff



-----------------------------------------------------------------------------

 Stack effect notation
 ---------------------

 Traditionally, stack languages use a "stack effect" notation to document how
 words affect the stack state, a kind of before-after transformation. here is
 a basic example showing how the word "add" works:

		stack   code
		      | 1 2 add
		    1 | 2 add
		  1 2 | add
		1 2 [add]			(a)
		    3 |				(b)


 Here the stack effect represents the difference between two states: the
 moment when the word is "read" (a) and the stack state after it is
 evaluated (b) and is written like this:

		( a b -- c )


 But, due to the fact that in Slang all three of the stack, code and namespace
 can be affected by words, we need an extended stack effect notation. to
 include at least the second most common case, the "code effect".
 To illustrate, here is an example of a word that has a simple code effect,
 the "+":

		stack   code
		      | 1 + 2
		    1 | + 2
		   1 [+] 2			(a)
		    3 |				(b)


 Here we see that in addition to affecting the stack, 2 is "pulled" from the
 code stream. To indicate this we will use "|" that splits the stack (left)
 and code (right) states, and write the stack effect for the word "+" like
 this:

		( a | b -- c |  )


 NOTE: this notation is currently used as a means to documenting words and is
 not interpreted in any way.



-------------------------------------------------------------------------------

 Blocks / Lists
 --------------

 Basic words for block manipulation:

 Get block length

		[ 1 2 3 ] len
				->	[ 1 2 3 ] 3


 Pop element form block tail

		[ 1 2 3 ] pop
				->	[ 1 2 ] 3


 Push element to block tail

		[ 1 2 3 ] 4 push
				->	[ 1 2 3 4 ]


 NOTE: all indexes can be negative values, these will indicate the
	position relative to the tail, -1 being the last element.

 Get element at position (0)

		[ 1 2 3 ] -1 at
				->	[ 1 2 3 ] 3


 Put element (123) at position (0)

		[ 1 2 3 ] 123 0 to
				->	[ 123 2 3 ]


 Put element (123) before position (0)

		[ 1 2 3 ] 123 0 before
				->	[ 123 1 2 3 ]


 Like before but puts the element after position

		[ 1 2 3 ] 123 0 after
				->	[ 1 123 2 3 ]


 Expand block to stack -- "block 2 stack"

		[ 1 2 3 ] b2s
				->	1 2 3


 Map a block/word to each element in a block

		[ 1 2 3 ] [ 1 add ] map
				->	[ 2 3 4 ]

 the returned value (stack) of the input block is put into the result
 block, this enables us to both remove (empty stack) and expand (more
 than one value) the resulting list...

		[ 1 2 3 4 ] [ dup ] map
				->	[ 1 1 2 2 3 3 4 4 ]

		[ 1 2 3 4 ] [ dup 2 gt ? [ ] else [ . ] ] map
				->	[ 3 4 ]


 this enables us to construct words like filter, which makes the code
 in the last example more readable:

		[ 1 2 3 4 ] [ 2 gt ] filter
				->	[ 3 4 ]

 Reduce enables us to take a list and "reduce" it to a single value...

		[ 1 2 3 4 ] \\add reduce
				->	10


-------------------------------------------------------------------------------

 Objects and namespaces
 ----------------------

 Get the namespace object...

		ns		-> namespace


 Set attribute (key-value pair) on object...

		o x 123 item!
				-> o

 Since almost all object words return the original object we can chain
 object operations like this:

 Create a variable word o and p and set them to empty objects...

		ns
			o {} item!
			p {} item!
		.

 Get attribute x value...

		o x item
				-> 123

 Test if attribute x exists...

		o x item?
				-> true

 Get block of attribute idents...

		o keys
				-> [ ... ]

 Get and remove an attribute value from o...

		o x popitem
				-> 123

 Set prototype of o to p

		o p proto!
				-> o

 Get prototype of o

		o proto
				-> p


-------------------------------------------------------------------------------
s2b drop               -- cleanup after docs...
ns {} proto! ns! .     -- keep new words in a seporate context...
--
-- With that out of the way, let\'s start with the bootstrap...

-- prepare the basic syntax for defining words...
ns
	-- Some shorthands...
	. ( x -- )
		[ drop ] item!
	rot2 ( .. x y -- x y .. )
		[ rot rot ] item!
	tor2 ( x y .. -- .. x y )
		[ tor tor ] item!

	-- Friendly exec...
	exec ( b -- ... )
		[ s2b pop _exec b2s ] item!
	-- Create a word...
	word! ( w b -- )
		[ rot2 ns tor2 item! . ] item!
	-- Word definition...
	-- syntax: :: <ident> <value>
	:: ( | w b -- | )
		[ \\word! \\exec 2 2 _swapN ] item!
.


-- misc...

:: true? ( a -- b ) [ not not true eq ]
:: false? ( a -- b ) [ not true? ]

-- we already have gt and eq, now let\'s define the rest...
:: ne ( a b -- c ) [ eq not ]
:: lt ( a b -- c ) [ swap gt ]
:: ge ( a b -- c ) [ lt not ]
:: le ( a b -- c ) [ gt not ]

:: inc ( a -- b ) [ 1 add ]
:: dec ( a -- b ) [ 1 sub ]
:: ! ( a -- b ) [ [ dup 1 ne ] ? [ dup 1 sub ! mul ] ]



-- Stack/code manipulation...

:: _swap ( x | y -- y | x ) [ 1 1 _swapN ]
:: _push ( x |  -- | x ) [ 0 _swapN ]
:: _pull (  | x -- x |  ) [ 0 swap _swapN ]

:: eval ( c -- ... ) [ lex prep exec ]
-- like exec but will run a block in current context...
:: b2c [ len rot b2s tor 0 _swapN ]

:: swap2 ( a _ b -- b _ a ) [ swap rot swap tor swap ]
:: dup2 ( a b -- a b a b ) [ dup swap2 dup rot swap2 tor swap ]

-- this is here for devel use only
:: _clear ( ... -- ) [ s2b print drop ] 
:: _stack_size ( -- l ) [ s2b len swap b2s tor ] 



-- Flow control...

-- Classic conditional word:
--   [ cond ] [ A ] [ B ] if
--
-- A bit too "polish" in my view ;)
:: if ( cond a b -- ... ) [ rot rot exec true? tor and tor or exec ]

-- Ternary operator, this can take two forms:
--   COND ? A
--   COND ? A else B
--
-- We will define this in stages, first the helpers:
-- run then block and drop \'else B\' if it exists...
:: _run_then ( a x | -- ... | x  )
	( a else | b -- ... | )
		[ \\exec swap dup \\else eq [ (drop else) drop \\drop _swap 6 ] and
				[ (run as-is) 1 _push 4 ] or
				b2s 0 _swapN ]
-- if \'else B\' exists, run it, else cleanup...
:: _run_else ( a | --  | a  )
	( b else | b -- ... | )
		[ drop dup \\else eq [ drop \\exec _swap 4 ] and
				[ 1 _push 2 ] or
				b2s 0 _swapN ]
-- And now the main operator...
-- NOTE: this may actually have one of three stack effects...
:: ? ( c | a -- | )
	( c | a -- ... | )
	( c | a else b -- ... | )
		[ exec [ _run_then 1 ] and [ swap _run_else 2 ] or b2s 2 _swapN ]



-- List/block 2\'nd gen stuff...

-- make a new block instance shorthand...
:: [] [ [ ] clone ]

-- insert element after index...
:: after ( b e i -- b ) [
	-- special case, when at end, need to push the alement after it...
	dup [ -1 eq ] ?
		[ . push ]
	else
		[ inc before ]]

-- NOTE: the "]]" in the last definition, it\'s a shorthand, it closes
--	ALL the open blocks to this point.
--	...thus it can be used ONLY as the very last word in a set.

-- push element to tail of block...
:: push ( b e -- b ) [ swap len rot swap tor to ]

-- Replace a pattern (p) in block with value (v)...
-- NOTE: this will replace ALL patterns...
:: replace ( l v p -- l ) [
	swap
	[ . \\VALUE ] clone
		swap 2 to
		rot
	-- XXX for some reason ? without else messes things up...
	[ dup \\PATTERN eq ? VALUE_BLOCK else [ ] ] clone
		swap 2 to
		tor 5 to
	map ]

-- Filter the block via a condition...
--
-- the condition block must have the folowing stack effect: elem -- bool
:: filter ( b c -- b ) [
	-- prepare the condition...
	[ dup \\TEST exec ] clone
		swap TEST replace
	-- prepare the template...
	[ TEST ? [  ] else [ . ] ] clone
		swap TEST replace
	map ]

:: reduce ( L b -- s ) [
	rot clone
	-- empty list, reduction is null...
	[ len 0 eq ] ?
		[ . tor . null ]
	-- reduction of list of len 1 is it\'s content, so just pop it...
	else [ [ len 1 eq ] ?
		[ tor . b2s ]
	-- and now recursively reduce the elements till the list is 1 in length...
	-- XXX ugly
	else [
		pop rot pop rot
			[] tor push tor push
		-- get and run the block...
		tor dup clone rot _exec
		-- process the result...
		pop rot . tor push tor
			reduce ]]

-- Create a block containing a range of numbers form 0 to n-1...
:: range ( n -- b ) [
	-- initial state...
	[ dup number? ] ? 
		[ [] swap ]
	-- get first elem...
	else
		[ 0 at ]
	-- we got to the end...
	[ dup 0 eq ] ? 
		drop
	-- dec push new and continue...
	else
		[ 1 sub 0 before range ]]

-- Sum up the elements of a block...
:: sum ( L -- s ) [ [ add ] reduce ]


-- Meta-word examples (experimental)...

-- Here is an infix operator example...
-- 	:: + ( a | b -- c |  ) [ \\exec 2 0 _swapN \\exec \\add 2 1 _swapN ]
-- now let\'s make a meta function to make things shorter...
:: infix: ( | op word -- | ) [
	[
		-- format the word definition...
		--     NAME WORD  ->  :: NAME WORD
		s2b \\:: -2 before b2s

		-- our template...
		-- exec the left side...
		[ \\exec 2 0 _swapN
				-- exec the right side and arragne the args for WORD...
				\\exec \\WORD 2 1 _swapN ] clone
			-- get the WORD and insert it into the template above (opsition 8)...
			swap WORD replace

		-- push to code / run
		3 0 _swapN 
	-- swap the arguments and the code to be executed...
	] \\exec 2 2 _swapN ]

-- Now making a word/2 an infix operator is trivial...
-- NOTE: these are at this point stupid and do not support priorities...
infix: + add
infix: - sub
infix: * mul
infix: / div

-- these need more thought...
infix: == eq
infix: != ne
infix: > gt
infix: < lt
infix: <= le
infix: >= ge

-- experimental...
infix: = word!


-- Prefix operation definition...
-- Example:
--		:: echo: ( | txt -- | ) [ \\_flip \\print _flip ]
-- swap stack and code untill the block finishes and consumes it's arguments
-- then swap them back...
:: prefix: ( | op word -- | ) [
	[
		-- format the word definition...
		--     NAME WORD  ->  :: NAME WORD
		s2b \\:: -2 before b2s

		-- the code template
		[ \\_flip \\exec \\WORD _flip ] clone
			swap WORD replace
			3 0 _swapN
	] \\exec 2 2 _swapN ]



-- Tests and examples...

-- Mandatory "hello word" word example...
:: hi ( -- ) [ "Hello World!" print drop ]

-- Create a block containg a range of numbers from f to t, inclusive...
:: range/2 ( f t -- b )
		[ dup2 swap sub swap . inc range swap [] swap push \\+ 0 before map ]

-- this will enable us to create ranges via 0 .. 4
infix: .. range/2

--:: range/3 ( a n s -- b )
--		[ swap range swap [] swap push \\* 0 before map ]

-- Execute block in a context...
-- synctx: context: <block>
prefix: context: [ ns {} proto! ns! exec ns proto ns! ]


`


var STARTUP = [[], BOOTSTRAP, 'lex', 'prep', '_exec', 'drop']


// build bootstrap...
var CONTEXT = {
	stack: [],
	code: STARTUP.slice(),
	ns: NAMESPACE,
	pre_ns: PRE_NAMESPACE,
}


// run bootstrap...
run(CONTEXT)


// convenience...
function _slang(code, context){
	context = context == null ? CONTEXT : context

	context.code = code
	return run(context).stack
}


function slang(code, context){
	context = context == null ? CONTEXT : context

	if(typeof(code) == typeof('abc')){
		code = [ '\\', code, 'lex', 'prep', 'exec' ]
	} else {
		code = [ code, 'prep', 'exec' ]
	}

	context.code = code
	return run(context).stack
}



/********************************************************** RSlang ***/
/*
var RS_PRE_NAMESPACE = {
	// XXX using the ";" here just for the experiment, in the real thing
	// 		if this thing pans out, that is, use indent... (a-la make/Python)
	// XXX this reads ahead at the moment, but it must read back...
	';': function(context){
		var line = []
		var code = context.code
		var cur = code.splice(0, 1)[0]
		while(cur != ';' && code.length > 0){
			line.push(cur)
			cur = code.splice(0, 1)[0]
		}
		
		context.code.splice.apply(context.code, [0, 0].concat(line.reverse()))
	},

	'[': PRE_NAMESPACE['['],
	'macro:': PRE_NAMESPACE['macro:'],
}

RS_CONTEXT = {
	stack: [],
	code: STARTUP.slice(),
	ns: NAMESPACE,
	pre_ns: PRE_NAMESPACE,
}

// NOTE: we use the traditional bootstrap for this...
run(RS_CONTEXT)

RS_CONTEXT.pre_ns = RS_PRE_NAMESPACE

function rslang(code, context){
	context = context == null ? RS_CONTEXT : context

	return slang(code, context)
}
//*/



/**********************************************************************
* vim:set ts=4 sw=4 spell :                                                */