On Mon, Sep 9, 2013 at 11:35 AM, Neil Toronto <neil.toro...@gmail.com> wrote: > Nice, and thanks for the explanation. Just to make sure I get it: does this > mean fully expanded TR modules are smaller?
Yes. > Does it reduce the number of generated contracts? No. > > > On 09/08/2013 12:24 PM, Sam Tobin-Hochstadt wrote: >> >> Typed Racket has to expand into code that registers the type of each >> module-top-level identifier in the global environment so that other >> modules can find the types to typecheck with. For example, this >> program: >> >> #lang typed/racket >> (provide x) >> (define: x : Integer 1) >> >> expands into (greatly simplified): >> >> #lang ... >> (#%provide x) >> (begin-for-syntax >> (declare #'x Integer-rep)) >> (define-values (x) 1) >> >> but what is `Integer-rep`? It needs to be an expression that >> _constructs_ the internal Typed Racket representation of the `Integer` >> type. Previously, that looked something like this: >> >> (make-Union (sort (list Negative-Fixnum-rep Positive-Fixnum-rep >> ...))) >> >> and so on and so forth for the components, all the way down to base >> types. You can imagine how this gets quite large, especially for >> large types. >> >> However, this is wasteful, because every Typed Racket program, at type >> checking time, defines a constant that's the representation of the >> `Integer` type, right here [1]. So instead of serializing an >> expression that constructs the same thing as `-Int`, we can just >> *reference* `-Int` in the expanded code. To make that possible, Typed >> Racket now builds a hash table [2] mapping types (really, their >> representations) to identifiers that denote those types. Then the >> serializer just consults this table [3]. >> >> It turns out that base types (but no others) already used basically >> this mechanism, by storing the identifier *in* the type >> representation. But that's now obsolete, and thus was removed in my >> subsequent commit. >> >> As a result, the type serialization is much smaller. >> >> [1] >> https://github.com/plt/racket/blob/master/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/types/numeric-tower.rkt#L107 >> [2] >> https://github.com/plt/racket/blob/master/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/types/base-abbrev.rkt#L23 >> [3] >> https://github.com/plt/racket/blob/master/pkgs/typed-racket-pkgs/typed-racket-lib/typed-racket/env/init-envs.rkt#L51 >> >> On Sat, Sep 7, 2013 at 3:20 PM, Neil Toronto <neil.toro...@gmail.com> >> wrote: >>> >>> On 09/06/2013 04:14 PM, sa...@racket-lang.org wrote: >>>> >>>> >>>> 56b372c Sam Tobin-Hochstadt <sa...@racket-lang.org> 2013-09-06 14:22 >>>> : >>>> | Remember types that are defined, and use them in serialization. >>>> | >>>> | This extends a facility already available for base types, >>>> | making that facility no longer strictly needed. >>>> | >>>> | Shrinks the zo size for the `math` package by almost 1MB. >>>> : >>>> M .../typed-racket/env/init-envs.rkt | 1 + >>>> M .../typed-racket/typecheck/def-export.rkt | 7 +- >>>> M .../typed-racket/typecheck/tc-toplevel.rkt | 31 +++--- >>>> M .../typed-racket/types/abbrev.rkt | 36 +++---- >>>> M .../typed-racket/types/base-abbrev.rkt | 12 ++- >>>> M .../typed-racket/types/numeric-tower.rkt | 108 >>>> +++++++++---------- >>> >>> >>> >>> Would you mind explaining this a little more? It sounds interesting, and >>> the >>> commit almost has my name in it. :) >>> >>> Neil ⊥ >>> > _________________________ Racket Developers list: http://lists.racket-lang.org/dev
