Re: Closures work.

[Ryan Gonzalez <rymg19@xxxxxxxxx>]

What exactly is the type of a closure then?

On September 28, 2015 12:56:08 AM CDT, Ori Bernstein <ori@xxxxxxxxxxxxxx> wrote:
>You can now capture environments. Fixing this has been a
>long time coming. It should make things like std.sort
>more useful, and simplify writing code that fills the
>same niche as C++'s std::algorithm
>
>
>Example below:
>
>    use std
>
>    const main = {
>        var x, y, yp, fn
>
>        x = 123
>        y = 234
>        yp = &y
>
>        fn = {
>            std.put("closure/pre:\tx={}, y={}, yp#={}\n", x, y, yp#)
>            x = 555
>            yp# = 666
>            std.put("closure/post:\tx={}, y={}, yp#={}\n", x, y, yp#)
>        }
>        std.put("outer/pre:\tx={}, y={}, yp#={}\n", x, y, yp#)
>        fn()
>        fn()
>        std.put("outer/post:\tx={}, y={}, yp#={}\n", x, y, yp#)
>    }
>
>You can build and run, and get this output:
>
>    $ mbld -b t t.myr
>    t...
>        6m -I /home/ori/bin/lib/myr t.myr 
>ld -o t /home/ori/bin/lib/myr/_myrrt.o t.o -L/home/ori/bin/lib/myr
>-lstd -lsys 
>    $ ./t
>    outer/pre:	  x=123, y=234, yp#=234
>    closure/pre:  x=123, y=234, yp#=234
>    closure/post: x=555, y=234, yp#=666
>    closure/pre:  x=555, y=234, yp#=666
>    closure/post: x=555, y=234, yp#=666
>    outer/post:	  x=123, y=666, yp#=666
>
>Note, this demonstrates a couple of interesting things:
>
>    1) The outer variables are not modified.
>2) We can get pointers to the outer environment if we need to mutate
>it.
> 3) The captured variables keep their values between invocations of the
>       closure
>
>The last point can maybe be used towards implementing generators. Or
>maybe I should
>make captures just be const.
>
>ABI-wise, this makes function pointers fat -- they have both an env
>pointer
>and a code pointer.
>
>-- 
>    Ori Bernstein

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