Re: [stack] XY implementation in JavaScript

Cool stuff.
I also implemented Cat in JavaScript http://cat-language.com/interpreter.html.
If you see anything you like feel free to reuse it, I've released the
source code into the public domain.

- Christopher

On Mon, Feb 16, 2009 at 7:35 PM, Chris Double <[email protected]> wrote:
> I've been playing around with an implementation of XY in JavaScript to
> explore client side web programming in a concatenative language. XY is
> one of Stevan Apter's language experiments:
>
> http://nsl.com/k/xy/xy.htm
>
> I've got the core of the language implemented and it's fun to play
> around with and use as a simple learning tool. A simple
> read/eval/print listener is available here:
>
> http://www.bluishcoder.co.nz/xyjs/xylistener.html
>
> Click somewhere on the page and then enter an expression. For example:
>
> [ 1 2 3 4 ] [ 2 * ] map .
>
> The '.' at the end will pop the last item off the X stack and print
> it. This implementation has large integers, using a big number
> implementation in JavaScript. So this works:
>
> ; fac dup 1 = [] [dup 1 - fac *] if ;
> 100 fac .
>
> Or you can use linrec:
>
> 10 [dup 1 =] [] [dup 1 -] [*] linrec alert
>
> This 'alert' word displays a pop up alert box. Operations that take a
> long time can hit the browsers 'kill long running scripts' message.
> I'll do a workaround for this at some point.
>
> If you do a 'view source' on the page you'll see the library of XY
> functions, taken from Stevan's page. The XY code is in an HTML script
> block of type 'text/x-xy':
>
> <script type="text/x-xy">
> ; pop { a } ;
> ; drop pop ;
> ; dip swap => / <= ;
> ; dup { a \a \a } ;
> ; swap { [a b] \b \a } ;
> </script>
>
> Not all of the included library works due to unimplemented core
> library functions. XY uses primitives based on K. I don't know what
> most of these are so I'm slowly working through them as I need to.
>
> There is a very simple JavaScript FFI to allow calling JavaScript
> functions. A 'js-global' word evals a given string and returns a
> JavaScript object:
>
> "document" js-global .
> => js([object HTMLDocument])
>
> A 'js-call' word calls a JavaScript function given an array of
> arguments, the 'this' object, and the function object on the stack:
>
> [ [ "hello" alert ] >js-function / 1000 / ] "window" js-global
> "window.setTimeout" js-global js-call
>
> The '>js-function' word converts an XY quotation to a JavaScript function.
>
> Continuations seem to work:
>
> [ "hello" . ] 0 call/cc "there" .
> => "hello"
> "there"
> dup /
> => "there"
> dup /
> => "there"
>
> In the listener Ctrl+Up and Ctrl+Down can be used to cycle through the
> history of last entered commands. There's not much error checking or
> reporting at the moment so errors tend to give obscure JavaScript
> related messages. Also I've mainly tested on Firefox so other browsers
> may or may not work. I believe Safari worked last time I tried.
>
> Another simple test page is:
>
> http://www.bluishcoder.co.nz/xyjs/xy.html
>
> Entering an expression and hitting 'Eval' will show each step as the
> expression is evaluated. For example, 1 2 dup + *, gives:
>
> 1 -> 2 dup + *
> 1 2 -> dup + *
> 1 2 -> { a \ a \ a } + *
> 1 2 { -> a \ a \ a } + *
> 1 2 { a -> \ a \ a } + *
> 1 2 { a \ -> a \ a } + *
> 1 2 { a \ a -> \ a } + *
> 1 2 { a \ a \ -> a } + *
> 1 2 { a \ a \ a -> } + *
> 1 -> \ 2 \ 2 + *
> 1 2 -> \ 2 + *
> 1 2 2 -> + *
> 1 4 -> *
> 4 ->
>
> The information on the left hand side of the '->' is the X stack, the
> right hand side is the Y queue.
>
> The core builtin words at the moment are listed here:
>
> http://www.bluishcoder.co.nz/xyjs/xy.txt
>
> There is a 'source' word that outputs a quotation containing the
> definition of a word:
>
> \ dup source .
> => [ { a \ a \ a } ]
>
> Any suggestions or ideas for improving/adding to this would be appreciated.
>
> Chris.
> --
> http://www.bluishcoder.co.nz
>
>