Re: Kawa proposed typing changes

[Per Bothner <per at bothner dot com>]

On 09/26/2009 11:21 AM, Helmut Eller wrote:
> * Per Bothner [2009-09-26 18:34+0200] writes:
> A minor question is if
>
>   (+ int (+ integer-literal integer-literal))
>
> has a different type than
>
>   (+ (+ int integer-literal) integer-literal)

Good question.  They both get int type:

(define (Foo (x :: int))
  (let ((y (+ x (+ 2 3)))
	(z (+ (+ x 5) 7)))
    (* y z)))

becomes:

Method name:"Foo" public static Signature: (int)int
Attribute "Code", length:81, max_stack:3, max_locals:3, code_length:15
  0: iload_0
  1: iconst_5
  2: iadd
  3: iload_0
  4: iconst_5
  5: iadd
  6: bipush 7
  8: iadd
  9: istore_2
 10: istore_1
 11: iload_1
 12: iload_2
 13: imul
 14: ireturn


> > > or string conversions are needed.
> >
> > What "string conversions" were you thinking about?
>
> Code like this:
>
> (define (foo (s java.lang.String)) s)
> (define (bar (s String)) (foo s))
> (define (baz (s gnu.lists.FString)) (bar s))
>
> (let ((x (string #\a)))
>    (list (instance? x java.lang.String)
>          (instance? (baz x) java.lang.String)))
>
> =>  (#f #t)
>
> Apparently x gets converted to java.lang.String somewhere along the way.
>
> > > Warnings about
> > > improper tail calls would also be nice.
> >
> > I'm concerned about too many false positives.
> > Any ides for avoiding that?
>
> If there is a compiler switch like [no-]warn-tail-calls it could be used
> as argument to with-compile-options on selected regions.  Or the
> compiler switch could also have arguments to name [un]interesting
> functions like
>
>   (with-compile-options warn-tail-calls: (foo) no-warn-tail-calls: (bar)
>     (if x
>         (foo) ; warn
>         (bar) ; ignore
>         ))
>
>
> BTW, it would be useful if Kawa had a disassemble function which takes
> procedures as argument.  That would be much more convenient than
> compiling to a class file and calling javap on it.

I agree.  More soon ...
--
	--Per Bothner
per@bothner.com   http://per.bothner.com/