I dont know much about J, but if I'm understanding correctly, you have
an implementation of J in Typed Racket?
And then you want to be able to infer more specialized cases in some
instances by pruning the type?
You might be able to do it with just plain macros in that case, which
would generate `ann` like William suggested to simplify some types.
Here's an example that does something similar for things like regexp:
https://blog.racket-lang.org/2017/04/type-tailoring.html
On Thu, Oct 31, 2019 at 5:06 PM Raoul Schorer wrote:
>
> Thank you very much for taking the time to help me.
> I am trying to write an extendable APL with full type inference and optional
> type annotation. Essentially, I am trying to compile J. J cannot be compiled
> efficiently because the ambiguities of its grammar lead to combinatory
> explosion of conditional branches in the resulting AST. The optional type
> annotations would therefore allow to prune the AST.
>
> You can find an example of this problem here:
> https://www.reddit.com/r/apljk/comments/bw8s49/question_regarding_the_impossibility_of_compiling/epwfgfq/
>
> In practice, instead of writing
>
> g =: + f (1 2 3 4 5)
>
> where f has an ambiguous type (Union (-> (Array Number) (Array Number)) (->
> (-> Array Number) (-> Array Number))), I would write something like
>
> g =: + 3::f (1 2 3 4 5)
>
> Where 3:: represents a type annotation meaning (-> (Array Number) (Array
> Number))
> Type inference in the language can however be derived directly from the
> execution model represented by the parse table at
> https://www.jsoftware.com/help/jforc/parsing_and_execution_ii.htm instead of
> a traditional inference algorithm. You can find my stub attempt with
> syntax/parse only at https://github.com/Rscho314/jacket/blob/master/parser.rkt
>
> Perhaps I should persevere with syntax/parse only? Or maybe it would be
> better to use type.expanders in the codegen phase instead of trying to do all
> at once with turnstile?
> I hope I am being clear. I'm just a hobbyist and have no formal CS education.
>
> Thanks again!
>
> Le mardi 29 octobre 2019 18:07:21 UTC+1, Raoul Schorer a écrit :
>>
>> Hi,
>>
>> I am attempting to expand to typed/racket from a custom language through
>> #lang turnstile. Unfortunately, the macro stepper isn't helping me much as
>> to how I should do that.
>> So far, this minimal example:
>>
>> #lang turnstile
>>
>> (require (only-in (prefix-in tr: typed/racket)
>> tr:#%module-begin
>> tr:Number
>> tr:#%datum)
>> turnstile/no-unicode)
>> (provide #%datum #%module-begin)
>>
>> ;[MODULE-BEGIN]
>> (define-syntax (#%module-begin stx)
>> (syntax-parse stx
>> [(_ prg) #`(tr:#%module-begin prg)]))
>>
>> ;[DATUM]
>> (define-typed-syntax #%datum
>> [(_ . n:number) >>
>>---
>>[/- (tr:#%datum . n) => tr:Number]])
>>
>> returns an error when I try to type a number in the REPL:
>> > 1
>> type-check: type name used out of context
>> type: tr:Number
>> in: tr:Number in: tr:Number
>>
>> I am a bit lost. Could someone give me pointers on how to expand to
>> typed/racket types using turnstile, please?
>>
>> Thanks a lot!
>> Raoul
>
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