On Mon, Feb 8, 2010 at 8:16 PM, John Meacham wrote:

...

I expect others have forethought and perhaps even experimented with such a language. Are there any dangers to be wary of that undo the entire endeavour?

There have been a couple papers published on it, the main sticking point seems to be tail call elimination. When targeting real hardware you always had the option of dropping to assembly to do a direct jump, but there isn't an equivalent in the JVM. If you look up tail call + jvm you will probably get a few hits. I believe there are even a couple haskell specific papers on the issue.

One of the easiest approaches to this comes from the scheme folks and I've been able to employ it fairly effectively in toy compilers. It doesn't require anything from the host language except exceptions and you can use it to evaluate spineless tagless g-machine frames mostly on the native/VM stack fairly easily. The biggest problem is the generated code bloat factor of about 2-3x. http://www.ccs.neu.edu/scheme/pubs/stackhack4.html http://www.cs.brown.edu/~sk/Publications/Papers/Published/pcmkf-cont-from-ge... -Edward Kmett

Tom Lokhorst wrote:

Also, I wonder if there is some efficient way of implementing the Lazy class, perhaps by having the Force method using runtime code generation to override itself. I don't know if this is possible, but I vaguely remember the Dynamic Language Runtime on .NET doing something like that.

.NET 4 (final release due in the next few months) will have a built-in lazy type. Ganesh =============================================================================== Please access the attached hyperlink for an important electronic communications disclaimer: http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html ===============================================================================

I don't think it's pure. I would definitely use a pure language on the JVM, but IIRC Open Quark / Cal is an impure language. For example, from the library documentation: "printLine :: String -> ()". -chris On 9 feb 2010, at 15:31, Tim Wawrzynczak wrote:

Perhaps this is similar to what you're looking for.

http://openquark.org/Open_Quark/Welcome.html

It's a pure, lazy language for the JVM. I haven't used it myself, but I would imagine that it would have a Java FFI.

Cheers, - Tim

On Mon, Feb 8, 2010 at 6:42 PM, Tony Morris wrote: I have hypothesised a pure, lazy language on the JVM and perhaps the .NET CLR with FFI to .NET/Java libraries. I foresee various problems but none that are catastrophic; just often requiring a compromises, sometimes very unattractive compromises. I have authored several libraries in the same vain as pure, lazy programming to run on the JVM in Java and Scala programming languages.

I expect others have forethought and perhaps even experimented with such a language. Are there any dangers to be wary of that undo the entire endeavour?

Thanks for any insights.

-- Tony Morris http://tmorris.net/

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On 10/02/2010, at 2:52 AM, Tim Wawrzynczak wrote:

Oops, you're right. It's not pure. Mea cupla for not reading more closely. I wonder how it deals with I/O, then? I don't see anything like Haskell's monads or Clean's uniqueness typing... but at a closer look it does appear to have an excellent Java FFI.

On Tue, Feb 9, 2010 at 9:44 AM, Chris Eidhof wrote: I don't think it's pure. I would definitely use a pure language on the JVM, but IIRC Open Quark / Cal is an impure language. For example, from the library documentation: "printLine :: String -> ()".

CAL is pure as long as you don't call Java functions with side effects, or functions like printLine -- rather like avoiding unsafePerformIO in Haskell. For my experimentation I use my own IO monad implementation, but you can generally use `seq` to control when IO happens. The Java FFI is good, although arguably verbose. Tom