Re: [racket-users] Help: How to check a typed/racket type in an untyped Racket contract?

2019-05-17 Thread Ben Greenman 
What happens if you provide the data structure from Typed Racket and
require it in an untyped module?

On 5/17/19, bruno cuconato  wrote:
> hi,
>
> I'm trying to use a data structure defined in a typed racket module in my
> untyped code.
>
> I'm want it to be accessible from a generic interface, so I'm using
> `define-generics`'s #:fast-defaults for
> dispatching to the proper methods (this might not be the best practice
> though, and if so I welcome corrections).
> to do this I need a predicate for the type of data structure, hence my
> replying to this thread.
>
> would Matthias' suggestion be the best long-term solution here?
>
>> It suggests we should provide these generated contracts (or grant access
> them) via a modicum of reflection.
>
> I couldn't get Sam's solution to work, most likely because I haven't read
> much about typed racket yet. I tried
> both
>
> `(define-predicate RBTree? (All (A) (RedBlackTree A))) `
>
> and
>
> `(define-predicate RBTree? (RedBlackTree Any)) `
>
> but none of them seem to work. even if I could get it to work,
> I still like Matthias' suggestion because I wouldn't need to create
> another module.
>
> cheers,
>
> -- bruno cuconato
>
> On Tuesday, August 8, 2017 at 8:17:11 PM UTC-3, Sam Tobin-Hochstadt wrote:
>>
>> One other suggestion: you can use `define-predicate` in a Typed Racket
>> module to create a predicate for any type that can be checked
>> immediately. So
>>
>> ```
>> (define-predicate dist? (Discrete-Dist Your-Type-Here))
>> ```
>>
>> should define the predicate you want.
>>
>> Sam
>>
>> On Fri, Jul 28, 2017 at 10:23 AM, James Geddes > > wrote:
>> > This is likely a typed-untyped interface newbie question.
>> >
>> > Briefly, how can I write a contract that asserts that some value has a
>> type that is defined in an imported typed/racket library?
>> >
>> > In more detail, I am using the math/distributions library, which is
>> written in typed/racket. My module is written in untyped Racket, and I'm
>> figuring out how to use contacts:
>> >
>> > #lang racket
>> > (require math/distributions) ;; this is a typed/racket library
>> >
>> > (define my-dist (discrete-dist '(thing-one thing-two)))
>> >
>> > (provide (contract-out [my-dist ???]))
>> >
>> >
>> > The question is: what should ??? be?. There is a distribution? predicate
>> >
>> but I'd quite like to be more specific: namely, that my-dist is a discrete
>>
>> distribution. In the source of math/distributions, the following type is
>> defined:
>> >
>> > (define-type (Discrete-Dist A) (discrete-dist-struct A A))
>> >
>> > but I don't know how this might translate into my untyped module.
>> >
>> >
>> > Any help much appreciated!
>> >
>> > James
>> >
>> >
>> >
>> >
>> > ---
>> > James Geddes
>> >
>> > --
>> > You received this message because you are subscribed to the Google
>> Groups "Racket Users" group.
>> > To unsubscribe from this group and stop receiving emails from it, send
>> an email to racket...@googlegroups.com .
>> > For more options, visit https://groups.google.com/d/optout.
>>
>
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Re: [racket-users] Help: How to check a typed/racket type in an untyped Racket contract?

2019-05-17 Thread bruno cuconato 
hi,

I'm trying to use a data structure defined in a typed racket module in my 
untyped code.

I'm want it to be accessible from a generic interface, so I'm using 
`define-generics`'s #:fast-defaults for
dispatching to the proper methods (this might not be the best practice 
though, and if so I welcome corrections). 
to do this I need a predicate for the type of data structure, hence my 
replying to this thread.

would Matthias' suggestion be the best long-term solution here?

> It suggests we should provide these generated contracts (or grant access 
them) via a modicum of reflection. 

I couldn't get Sam's solution to work, most likely because I haven't read 
much about typed racket yet. I tried
both

`(define-predicate RBTree? (All (A) (RedBlackTree A))) `

and

`(define-predicate RBTree? (RedBlackTree Any)) `

but none of them seem to work. even if I could get it to work, 
I still like Matthias' suggestion because I wouldn't need to create
another module.

cheers,

-- bruno cuconato

On Tuesday, August 8, 2017 at 8:17:11 PM UTC-3, Sam Tobin-Hochstadt wrote:
>
> One other suggestion: you can use `define-predicate` in a Typed Racket 
> module to create a predicate for any type that can be checked 
> immediately. So 
>
> ``` 
> (define-predicate dist? (Discrete-Dist Your-Type-Here)) 
> ``` 
>
> should define the predicate you want. 
>
> Sam 
>
> On Fri, Jul 28, 2017 at 10:23 AM, James Geddes  > wrote: 
> > This is likely a typed-untyped interface newbie question. 
> > 
> > Briefly, how can I write a contract that asserts that some value has a 
> type that is defined in an imported typed/racket library? 
> > 
> > In more detail, I am using the math/distributions library, which is 
> written in typed/racket. My module is written in untyped Racket, and I'm 
> figuring out how to use contacts: 
> > 
> > #lang racket 
> > (require math/distributions) ;; this is a typed/racket library 
> > 
> > (define my-dist (discrete-dist '(thing-one thing-two))) 
> > 
> > (provide (contract-out [my-dist ???])) 
> > 
> > 
> > The question is: what should ??? be?. There is a distribution? predicate 
> but I'd quite like to be more specific: namely, that my-dist is a discrete 
> distribution. In the source of math/distributions, the following type is 
> defined: 
> > 
> > (define-type (Discrete-Dist A) (discrete-dist-struct A A)) 
> > 
> > but I don't know how this might translate into my untyped module. 
> > 
> > 
> > Any help much appreciated! 
> > 
> > James 
> > 
> > 
> > 
> > 
> > --- 
> > James Geddes 
> > 
> > -- 
> > You received this message because you are subscribed to the Google 
> Groups "Racket Users" group. 
> > To unsubscribe from this group and stop receiving emails from it, send 
> an email to racket...@googlegroups.com . 
> > For more options, visit https://groups.google.com/d/optout. 
>

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Re: [racket-users] Help: How to check a typed/racket type in an untyped Racket contract?

2017-08-08 Thread Sam Tobin-Hochstadt 
One other suggestion: you can use `define-predicate` in a Typed Racket
module to create a predicate for any type that can be checked
immediately. So

```
(define-predicate dist? (Discrete-Dist Your-Type-Here))
```

should define the predicate you want.

Sam

On Fri, Jul 28, 2017 at 10:23 AM, James Geddes  wrote:
> This is likely a typed-untyped interface newbie question.
>
> Briefly, how can I write a contract that asserts that some value has a type 
> that is defined in an imported typed/racket library?
>
> In more detail, I am using the math/distributions library, which is written 
> in typed/racket. My module is written in untyped Racket, and I'm figuring out 
> how to use contacts:
>
> #lang racket
> (require math/distributions) ;; this is a typed/racket library
>
> (define my-dist (discrete-dist '(thing-one thing-two)))
>
> (provide (contract-out [my-dist ???]))
>
>
> The question is: what should ??? be?. There is a distribution? predicate but 
> I'd quite like to be more specific: namely, that my-dist is a discrete 
> distribution. In the source of math/distributions, the following type is 
> defined:
>
> (define-type (Discrete-Dist A) (discrete-dist-struct A A))
>
> but I don't know how this might translate into my untyped module.
>
>
> Any help much appreciated!
>
> James
>
>
>
>
> ---
> James Geddes
>
> --
> You received this message because you are subscribed to the Google Groups 
> "Racket Users" group.
> To unsubscribe from this group and stop receiving emails from it, send an 
> email to racket-users+unsubscr...@googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.

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Re: [racket-users] Help: How to check a typed/racket type in an untyped Racket contract?

2017-07-31 Thread Matthias Felleisen 


> On Jul 31, 2017, at 5:27 AM, James Geddes  wrote:
> 
> 
> Matthias,
> 
> Thank you, that's really helpful, both for letting me know I'm not being an 
> idiot (always welcome!) and for the example code, which makes me realise I 
> should learn about exceptions next.
> 
> Many thanks again,
> 
> James


Writing predicates via exceptions is a less than ideal situation. 

The proper solution would be to change Typed Racket to provide
the contracts that come with exported identifiers or similar 
solutions. 

But knowing how exceptions work is a ‘good thing.’ 

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Re: [racket-users] Help: How to check a typed/racket type in an untyped Racket contract?

2017-07-31 Thread James Geddes 

Matthias,

Thank you, that's really helpful, both for letting me know I'm not being an 
idiot (always welcome!) and for the example code, which makes me realise I 
should learn about exceptions next.

Many thanks again,

James


---
James Geddes

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Re: [racket-users] Help: How to check a typed/racket type in an untyped Racket contract?

2017-07-28 Thread Matthias Felleisen 

After some poking around, here is what I can offer:

#lang racket

(module predicates racket
  (provide discrete-dist-thing?)
  
  ;; -
  ;; dependencies 
  (require math/distributions)

  ;; -
  ;; implementation 
  (define (discrete-dist-thing? x)
(define is-it-discrete-dist-values
  (with-handlers ([exn:fail? (lambda (xn)
   (define msg (exn-message xn))
   (if (regexp-match? #rx"expected: 
discrete-dist-struct" msg)
   #false
   (raise xn)))])
(discrete-dist-values x)))
(and is-it-discrete-dist-values
 (andmap symbol? is-it-discrete-dist-values)
 (let ([probs (discrete-dist-probs x)])
   (and (andmap flonum? probs) (andmap positive? probs))

(module server racket
  (require (submod ".." predicates))
  (provide
   (contract-out
[d discrete-dist-thing?]))

  ;; -
  ;; dependencies 
  (require math/distributions)

  ;; -
  ;; implementation 
  (define d (discrete-dist '(one two

(require 'server)
d


Watch for symbol?. You want to abstract over that. 



> On Jul 28, 2017, at 12:16 PM, Matthias Felleisen  wrote:
> 
>> 
>> On Jul 28, 2017, at 11:23 AM, James Geddes  wrote:
>> 
>> This is likely a typed-untyped interface newbie question.
>> 
>> Briefly, how can I write a contract that asserts that some value has a type 
>> that is defined in an imported typed/racket library?
>> 
>> In more detail, I am using the math/distributions library, which is written 
>> in typed/racket. My module is written in untyped Racket, and I'm figuring 
>> out how to use contacts:
>> 
>> #lang racket
>> (require math/distributions) ;; this is a typed/racket library
>> 
>> (define my-dist (discrete-dist '(thing-one thing-two)))
>> 
>> (provide (contract-out [my-dist ???]))
>> 
>> 
>> The question is: what should ??? be?. There is a distribution? predicate but 
>> I'd quite like to be more specific: namely, that my-dist is a discrete 
>> distribution. In the source of math/distributions, the following type is 
>> defined:
>> 
>>  (define-type (Discrete-Dist A) (discrete-dist-struct A A))
>> 
>> but I don't know how this might translate into my untyped module.
>> 
>> 
>> Any help much appreciated!
> 
> 
> This is a great question. It suggests we should provide these generated 
> contracts (or grant access them) via a modicum of reflection. 
> 
> In the meantime, you want to look at the result type of discrete-dist, which 
> is the type (Discrete-Dist A). This is turn is a subtype of (dist A A), which 
> is opaque/undocumented/I can’t find it in the code base (on the fly). It’s 
> not exported. So at the moment, your will have to take the fall if someone 
> abuses it. 
> 
> — Matthias
> 
> -- 
> You received this message because you are subscribed to the Google Groups 
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Re: [racket-users] Help: How to check a typed/racket type in an untyped Racket contract?

2017-07-28 Thread Matthias Felleisen 

> On Jul 28, 2017, at 11:23 AM, James Geddes  wrote:
> 
> This is likely a typed-untyped interface newbie question.
> 
> Briefly, how can I write a contract that asserts that some value has a type 
> that is defined in an imported typed/racket library?
> 
> In more detail, I am using the math/distributions library, which is written 
> in typed/racket. My module is written in untyped Racket, and I'm figuring out 
> how to use contacts:
> 
> #lang racket
> (require math/distributions) ;; this is a typed/racket library
> 
> (define my-dist (discrete-dist '(thing-one thing-two)))
> 
> (provide (contract-out [my-dist ???]))
> 
> 
> The question is: what should ??? be?. There is a distribution? predicate but 
> I'd quite like to be more specific: namely, that my-dist is a discrete 
> distribution. In the source of math/distributions, the following type is 
> defined:
> 
>   (define-type (Discrete-Dist A) (discrete-dist-struct A A))
> 
> but I don't know how this might translate into my untyped module.
> 
> 
> Any help much appreciated!


This is a great question. It suggests we should provide these generated 
contracts (or grant access them) via a modicum of reflection. 

In the meantime, you want to look at the result type of discrete-dist, which is 
the type (Discrete-Dist A). This is turn is a subtype of (dist A A), which is 
opaque/undocumented/I can’t find it in the code base (on the fly). It’s not 
exported. So at the moment, your will have to take the fall if someone abuses 
it. 

— Matthias

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