Re: [racket-users] Function contract that cares only about the return value?

[David Storrs]

Dangit, how did I miss that?  I fail reading comprehension forever.

Thanks, guys.

On Tue, Jun 13, 2017 at 11:26 AM, Ben Greenman 
wrote:

> unconstrained-domain->
>
> http://docs.racket-lang.org/reference/function-contracts.
> html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%
> 29._unconstrained-domain-~3e%29%29
>
>
> On Tue, Jun 13, 2017 at 11:24 AM, David Storrs 
> wrote:
>
>> Suppose the following trivial function:
>>
>> (define/contract (foo func)
>>   (-> (-> any/c ... any/c) #t)
>>   #t)
>>
>> This is trying (and failing) to express the idea "foo takes a processor
>> function.  I don't care what arguments the processor requires (that's the
>> caller's job) but the processor must return a singular result."
>>
>> What would be the correct contract for foo?  I've been through the
>> section on function contracts; the above was my first guess but this fails:
>>
>> (foo identity)
>> ; foo: contract violation
>> ;   expected: a procedure that accepts 0 non-keyword arguments and
>> arbitrarily
>> ; many more
>> ;   given: #
>> ;   identity accepts: 1 argument
>> ;   in: the 1st argument of
>> ;   (-> (-> any/c ... any/c) #t)
>> ;   contract from: (function foo)
>> ;   blaming: top-level
>> ;(assuming the contract is correct)
>> ;   at: readline-input:8.18
>> ; [,bt for context]
>> ->
>>
>>
>> I also tried this, which apparently isn't even legal syntax:
>>
>> (define/contract (foo func)
>>   (-> (-> any any/c) #t)
>>   #t)
>> ; readline-input:10:33: any: use of 'any' outside the range of an arrow
>> ;   contract
>> ;   in: any
>> ; [,bt for context]
>>
>>
>>
>> --
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>> "Racket Users" group.
>> To unsubscribe from this group and stop receiving emails from it, send an
>> email to racket-users+unsubscr...@googlegroups.com.
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>>
>
>

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[racket-users] Function contract that cares only about the return value?

[David Storrs]

Suppose the following trivial function:

(define/contract (foo func)
  (-> (-> any/c ... any/c) #t)
  #t)

This is trying (and failing) to express the idea "foo takes a processor
function.  I don't care what arguments the processor requires (that's the
caller's job) but the processor must return a singular result."

What would be the correct contract for foo?  I've been through the section
on function contracts; the above was my first guess but this fails:

(foo identity)
; foo: contract violation
;   expected: a procedure that accepts 0 non-keyword arguments and
arbitrarily
; many more
;   given: #
;   identity accepts: 1 argument
;   in: the 1st argument of
;   (-> (-> any/c ... any/c) #t)
;   contract from: (function foo)
;   blaming: top-level
;(assuming the contract is correct)
;   at: readline-input:8.18
; [,bt for context]
->


I also tried this, which apparently isn't even legal syntax:

(define/contract (foo func)
  (-> (-> any any/c) #t)
  #t)
; readline-input:10:33: any: use of 'any' outside the range of an arrow
;   contract
;   in: any
; [,bt for context]

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Re: [racket-users] Function contract that cares only about the return value?

[Sam Tobin-Hochstadt]

I think you want the `unconstrained-domain->` contract.

Sam

On Tue, Jun 13, 2017 at 11:24 AM, David Storrs  wrote:
> Suppose the following trivial function:
>
> (define/contract (foo func)
>   (-> (-> any/c ... any/c) #t)
>   #t)
>
> This is trying (and failing) to express the idea "foo takes a processor
> function.  I don't care what arguments the processor requires (that's the
> caller's job) but the processor must return a singular result."
>
> What would be the correct contract for foo?  I've been through the section
> on function contracts; the above was my first guess but this fails:
>
> (foo identity)
> ; foo: contract violation
> ;   expected: a procedure that accepts 0 non-keyword arguments and
> arbitrarily
> ; many more
> ;   given: #
> ;   identity accepts: 1 argument
> ;   in: the 1st argument of
> ;   (-> (-> any/c ... any/c) #t)
> ;   contract from: (function foo)
> ;   blaming: top-level
> ;(assuming the contract is correct)
> ;   at: readline-input:8.18
> ; [,bt for context]
> ->
>
>
> I also tried this, which apparently isn't even legal syntax:
>
> (define/contract (foo func)
>   (-> (-> any any/c) #t)
>   #t)
> ; readline-input:10:33: any: use of 'any' outside the range of an arrow
> ;   contract
> ;   in: any
> ; [,bt for context]
>
>
>
> --
> 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.
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Re: [racket-users] Function contract that cares only about the return value?

[Ben Greenman]

unconstrained-domain->

http://docs.racket-lang.org/reference/function-contracts.html#%28form._%28%28lib._racket%2Fcontract%2Fbase..rkt%29._unconstrained-domain-~3e%29%29


On Tue, Jun 13, 2017 at 11:24 AM, David Storrs 
wrote:

> Suppose the following trivial function:
>
> (define/contract (foo func)
>   (-> (-> any/c ... any/c) #t)
>   #t)
>
> This is trying (and failing) to express the idea "foo takes a processor
> function.  I don't care what arguments the processor requires (that's the
> caller's job) but the processor must return a singular result."
>
> What would be the correct contract for foo?  I've been through the section
> on function contracts; the above was my first guess but this fails:
>
> (foo identity)
> ; foo: contract violation
> ;   expected: a procedure that accepts 0 non-keyword arguments and
> arbitrarily
> ; many more
> ;   given: #
> ;   identity accepts: 1 argument
> ;   in: the 1st argument of
> ;   (-> (-> any/c ... any/c) #t)
> ;   contract from: (function foo)
> ;   blaming: top-level
> ;(assuming the contract is correct)
> ;   at: readline-input:8.18
> ; [,bt for context]
> ->
>
>
> I also tried this, which apparently isn't even legal syntax:
>
> (define/contract (foo func)
>   (-> (-> any any/c) #t)
>   #t)
> ; readline-input:10:33: any: use of 'any' outside the range of an arrow
> ;   contract
> ;   in: any
> ; [,bt for context]
>
>
>
> --
> 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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