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From: Sonny To <son.c.to@gmail.com>
To: Per Bothner <per@bothner.com>
Cc: Kawa mailing list <kawa@sourceware.org>
Subject: Re: using lambda to implement one method interface
Date: Sun, 17 Sep 2017 18:54:00 -0000	[thread overview]
Message-ID: <CAJxjsJvOTR+iOpf=jXVJqez+1cNQH2xxk67VRtOeLeQ-840P5g@mail.gmail.com> (raw)
In-Reply-To: <5319927a-872b-bf10-59a5-10b25b24343b@bothner.com>

this is a big problem for my use case...

i wouldn't be able to do something like this on android at runtime

(object (java.lang.Runnable)
((run (a ::void))::void
         (+ 1 1)
         ))



On Sun, Sep 17, 2017 at 9:50 AM, Per Bothner <per@bothner.com> wrote:
> On 09/17/2017 09:03 AM, Sonny To wrote:
>>
>> Thanks for the explanation. However, I'm still not clear about
>> compile-time. I'm evaluating this in the TelnetRepl. its interpreted
>> no?
>
>
> Yes and no. "Compile-time" is when the Scheme expression is parsed,
> analyzed, and (normally) translated to JVM bytecode.  On most platforms,
> even when you type an expression into a REPL, it gets translated to bytecode
> and then loaded on-the-fly using java.lang.ClassLoader.defineClass.
>
> Because Android doesn't have ClassLoader.defineClass (because it uses dex),
> we don't translate REPL input to bytecode. Instead, there is an
> interpreter that evaluates to tree (Expression) form of the expression.
>
> Determining when "SAM-conversion" (converting lambda to anonymous class)
> is allowed is done at compile-time.  On most platforms, creating the
> anonymous class is also done at time-time.  On Android, the last step is
> deferred to run-time, using a ProcedurallProxy class, but that only supports
> converting a lambda to an interface, not a class.
>
> It probably wouldn't be difficult to use ProcedurallProxy at run-time to
> convert
> a procedure value to a class instance. However, it would require changes to
> error handling: Instead of compiling a simple cast, we have to compile to a
> more
> complex (and slower) procedure.  There is also a question of what warning
> messages,
> if any to emit.  Perhaps worth revisiting if/when we implement
> "Optional strict typing along with an explicit dynamic type"
> (https://www.gnu.org/software/kawa/Ideas-and-tasks.html#Optional-strict-typing-along-with-an-explicit-dynamic-type).
>
> (The 'dynamic' type is already partially supported.)
>
> --
>         --Per Bothner
> per@bothner.com   http://per.bothner.com/

  reply	other threads:[~2017-09-17 18:54 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-17 15:32 Sonny To
2017-09-17 15:38 ` Sonny To
2017-09-17 15:59   ` Per Bothner
2017-09-17 16:04     ` Sonny To
2017-09-17 16:50       ` Per Bothner
2017-09-17 18:54         ` Sonny To [this message]
2017-09-17 20:02           ` Per Bothner
2017-09-18  6:35             ` Sonny To
2017-09-18  8:17               ` Sonny To
2017-09-18 13:59                 ` Per Bothner
2017-09-18 11:22               ` Sudarshan S Chawathe
2017-09-18 14:24                 ` Per Bothner
2017-09-18 14:31                   ` Sudarshan S Chawathe

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