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New Post: Suitability for real-time applications

sonelliot — Mon, 08 Apr 2013 02:45:11 GMT

Thanks Leppie. That works nicely. I also discovered that my console app couldn't handle multiple lines of input (doh!) I made it read input a little bit more intelligently, looking for an matching number of open and close brackets before submitting the input to the evaluator.

New Post: Suitability for real-time applications

leppie — Sat, 06 Apr 2013 08:42:32 GMT

I managed to recreate the error :)

What effectively happens is that you are calling:

ii.Eval("(import (ironscheme clr)) (let ((str (clr-new String \"\"))) str");

The evaluator can only handle a single (S) expression and you are passing 2 in.

This is easy to handle. Just wrap your input string with the following:

input = string.Format("(begin {0} \n)", input);

My previous assumption was incorrect :)

New Post: Suitability for real-time applications

sonelliot — Sat, 06 Apr 2013 03:19:58 GMT

Sorry mis-post.

New Post: Suitability for real-time applications

sonelliot — Sat, 06 Apr 2013 03:14:20 GMT

Thanks Leppie that works great. I can now control the game at runtime from an IronScheme console!

In my little console application that uses the InteractionService I have been catching exceptions and printing them to the output. This works well for fairly well-known problems like undefined symbols, which typically print out something like this:

&undefined
&message: "attempted to use undefined symbol"
&irritants: (beh)

But I also see a lot of SyntaxErrorException being thrown which are spit out a large stack trace and aren't very helpful. Do you have any words of wisdom for my approach here? I am currently in the process of building IronScheme from source so that I can attach the debugger and break when the exceptions are being thrown. I'm hoping this will help me discover what I've done wrong and potentially if there is a way of making those error messages a bit nicer.

If you're interested, this is an example issue:

(import (rnrs) (ironscheme clr))
(let ((str (clr-new String "")))
  str)

If I run this with the provided IronScheme console I see:

Unhandled CLR exception during evaluation:
CLR Exception: System.InvalidCastException
System.InvalidCastException: Unable to cast object of type 'System.String' to type 'System.Char[]'.
   at eval-core(031).Initialize(CodeContext )
   at #.ironscheme.exceptions::dynamic-wind(Object in, Object proc, Object out)
   at #.ironscheme.exceptions::dynamic-wind(Object in, Object proc, Object out)
   at IronScheme.Runtime.Builtins.CallWithCurrentContinuation(Object fc1)
   at IronScheme.Runtime.R6RS.Exceptions.WithClrExceptionHandler(Object handler, Object thunk)

Which is quite helpful because it tells me what went wrong. But running it with my remote console app, I see:

Microsoft.Scripting.SyntaxErrorException: Exception of type 'Microsoft.Scripting.SyntaxErrorException' was thrown.
   at Microsoft.Scripting.LanguageContext.CompileSourceCode(SourceUnit sourceUnit, CompilerOptions options, ErrorSink errorSink)
   at Microsoft.Scripting.Hosting.ScriptEngine.CompileSourceUnit(SourceUnit sourceUnit, IScriptModule module)
   at Microsoft.Scripting.Hosting.ScriptEngine.CompileExpression(String expression, IScriptModule module)
   at IronScheme.RuntimeExtensions.EvalWithEnvironment(String expr, String importspec, Object[] args)
   at IronScheme.Remoting.Server.InteractionService.EvalInternal(String expr, String importspec, Object[] args)

Which is less useful.

Edit: I'm thinking that using the InteractionService might not be the best way to go. Would it be difficult to modify the provided IronScheme console to connect to a remote server?

New Post: Suitability for real-time applications

leppie — Fri, 05 Apr 2013 05:49:08 GMT

Yes, define will be problematic with arguments. Will see if I can fix that :)

The better way would be to use parameters, and just set the value. Eg:

In Scheme:

(define some-object (make-parameter #f))

From C#:

"(some-object {0})".Eval(instance);

Then in Scheme you would use it like:

(let ((o (some-object))) ...)

This way Scheme knows about the variable.

New Post: Suitability for real-time applications

sonelliot — Fri, 05 Apr 2013 05:45:18 GMT

Thanks Leppie, that did the trick. I did come across one irregularity. I had to do this to get it to work:

"(define some-object '())".Eval();
"(set! some-object {0})".Eval(instance);

When I tried to pass the CLR object to the define evaluation it threw this error:

{&message: "no expression in body"
&syntax:
  form: ()
  subform: #f
}

Not sure why it did this? It seems like a reasonable call to me..

New Post: Suitability for real-time applications

leppie — Fri, 05 Apr 2013 04:22:13 GMT

Hi

There are various ways to share data.

If you want to to pass the an instance (of anything/object) from C#, you can do:

"(some-proc {0})".Eval(instance);

some-proc will receive the instance as is. {0} is effectively bound to that instance.

If you want to get some data from Scheme, you can just call a normal CLR method/property:

(let ((o (clr-static-call Foo Bar))) ...)

If you have a different scenario, let me know :)

Cheers

leppie

New Post: Suitability for real-time applications

sonelliot — Fri, 05 Apr 2013 04:15:12 GMT

Hi Leppie,

As a follow-up, I've been doing some prototyping embedding IronScheme into a running game and using it to execute code and commands at run-time. The problem I am now struggling with is sharing objects from the running application in the interactive Scheme environment. I understand that you can use clr-new to create instances of CLR types. Is it possible to create an object in C# and then share it with the IronScheme environment?

New Post: IronScheme Installable?

mayureshkathe — Thu, 04 Apr 2013 04:28:24 GMT

Will there be an "installable" for the newer builds soon?

New Post: How about a roadmap?

mayureshkathe — Thu, 04 Apr 2013 04:13:37 GMT

how about support for creating graphical elements, like http://showui.codeplex.com/

New Post: Suitability for real-time applications

sonelliot — Mon, 25 Mar 2013 12:34:11 GMT

Haha, yes I guess you are right, JIT-compiled languages aren't really real-time, or so-to-speak. Probably what I was after was an indication of it's runtime performance in comparison to C#, which would be the language I would typically be using to work with MonoGame.

New Post: How about a roadmap?

leppie — Mon, 25 Mar 2013 10:39:55 GMT

I have nothing specific planned at the moment.

Feel free to suggest required features.

Cheers

leppie

New Post: 100% R6RS?

leppie — Mon, 25 Mar 2013 10:38:12 GMT

Hi

Like previously discussed with you, making IronScheme 100% compliant (basically meaning full support for continuations) would break .NET interoperability.

If you do that, you basically have just another Scheme, but losing out on the .NET interoperability niche.

There is no way to make .NET continuation friendly unless you rewrite and recompile all of .NET to support it (say via CPS, if this is even possible for MSIL based bytecode).

Cheers

leppie

New Post: Suitability for real-time applications

leppie — Mon, 25 Mar 2013 10:27:22 GMT

It depends on your definition of 'real-time' :)

If you feel C# is real-time, then yes, IronScheme would fall into the same category as long as you dont use `eval` during runtime.

But almost any language with a JIT compiler is not really strictly real-time :)

On Mon, Mar 25, 2013 at 11:43 AM, sonelliot <notifications@codeplex.com> wrote:

From: sonelliot

I have been looking for an implementation of Scheme on the CLR that would be suitable for real-time applications. As a hobby I was going to experiment using Scheme for game development. It would be really cool to be able to use a .NET implementation since then I would have access to the amazing MonoGame!

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New Post: Suitability for real-time applications

sonelliot — Mon, 25 Mar 2013 09:43:39 GMT

I have been looking for an implementation of Scheme on the CLR that would be suitable for real-time applications. As a hobby I was going to experiment using Scheme for game development. It would be really cool to be able to use a .NET implementation since then I would have access to the amazing MonoGame!

New Post: 100% R6RS?

mayureshkathe — Thu, 28 Feb 2013 10:20:18 GMT

Umnn, what would it take to say "IronScheme is 100% R6RS compliant"?

New Post: Windows UI development using IronScheme

mayureshkathe — Wed, 27 Feb 2013 06:29:05 GMT

Wonder if IronScheme can do something like http://showui.codeplex.com/

New Post: Using IronScheme with "Simply Scheme"

leppie — Mon, 25 Feb 2013 08:55:03 GMT

The best I can recommend for IronScheme/R6RS is TSPL4.

You can get the entire text at: http://www.scheme.com/tspl4/

BTW, Chez Petite also works on Windows.

On Mon, Feb 25, 2013 at 10:19 AM, mayureshkathe <notifications@codeplex.com> wrote:

From: mayureshkathe

leppie, not intending to belittle you nor flatter you, but, I believe IronScheme definitely has potential, just that there are very few people (only you I suppose) working on it at the moment, I intend to remedie that in the near future by joining your project (as I'd promised a while back).

I would prefer to stick around with IronScheme, probably start-off with something simple like "The Little Schemer", "The Seasoned Schemer" and "The Reasoned Schemer" and then head over to SICP.

Thanks.

PS: I really hate Racket, it's quite un-Windows like.

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New Post: Using IronScheme with "Simply Scheme"

mayureshkathe — Mon, 25 Feb 2013 08:19:45 GMT

leppie, not intending to belittle you nor flatter you, but, I believe IronScheme definitely has potential, just that there are very few people (only you I suppose) working on it at the moment, I intend to remedie that in the near future by joining your project (as I'd promised a while back).

I would prefer to stick around with IronScheme, probably start-off with something simple like "The Little Schemer", "The Seasoned Schemer" and "The Reasoned Schemer" and then head over to SICP.

Thanks.

PS: I really hate Racket, it's quite un-Windows like.

New Post: Using IronScheme with "Simply Scheme"

leppie — Mon, 25 Feb 2013 08:04:05 GMT

From what I gather, the best way to learn Scheme is via one of the Racket supported courses (SICP, HTDP, EOPL, etc).

Also Racket runs on Windows and has very nice debugger support.

On Mon, Feb 25, 2013 at 9:51 AM, mayureshkathe <notifications@codeplex.com> wrote:

From: mayureshkathe

Gah, which introductory book would you recommend?
SICP seems quite tough, but, if it's much better supported than Simply Scheme, I'll walk the tough path willingly... :-)

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