[racket] problem with map example in docs of typed/racket

Ha, Thanks. I'll try. 
Jos 

> -----Original Message-----
> From: Hari Prashanth [mailto:krhari at ccs.neu.edu] 
> Sent: 26 August 2010 22:18
> To: Jos Koot
> Cc: PLT-Scheme Mailing List
> Subject: Re: [racket] problem with map example in docs of typed/racket
> 
> 1. You need to explicitly instantiate the list function like this.
> 
> (my-map (inst list (U Integer Symbol)) '(1 2 3) '(a b c))
> 
> 2. If you take a closer look at the type error you will 
> figure out why it is.
> 
> ----- Original Message -----
> From: "Jos Koot" <jos.koot at telefonica.net>
> To: "Hari Prashanth" <krhari at ccs.neu.edu>
> Cc: "PLT-Scheme Mailing List" <users at lists.racket-lang.org>
> Sent: Thursday, August 26, 2010 3:54:46 PM GMT -05:00 
> US/Canada Eastern
> Subject: RE: [racket] problem with map example in docs of typed/racket
> 
> Two things worry me:
> 
> In your version,
> (my-map list '(1 2 3) '(a b c))
> results in an exception.
> 
> 2:
> Replacing the internal calls to map by calls to my-map does 
> not pass check-syntax.
> 
> It may be my ignorance, though. I just started looking into TR.
> 
> Jos  
> 
> > -----Original Message-----
> > From: Hari Prashanth [mailto:krhari at ccs.neu.edu]
> > Sent: 26 August 2010 20:17
> > To: Jos Koot
> > Cc: PLT-Scheme Mailing List
> > Subject: Re: [racket] problem with map example in docs of 
> typed/racket
> > 
> > I think the example should be changed to
> > 
> > (: my-map
> >    (All (C A B ...)
> >         ((A B ... B -> C) (Listof A) (Listof B) ... B -> 
> (Listof C)))) 
> > (define (my-map f as . bss)
> >   (if (or (null? as) (ormap null? bss))
> >       null
> >       (cons (apply f (car as) (map car bss))
> >             (apply my-map f (cdr as) (map cdr bss)))))
> > 
> > 
> > Hari
> > 
> > ----- Original Message -----
> > From: "Jos Koot" <jos.koot at telefonica.net>
> > To: "PLT-Scheme Mailing List" <users at lists.racket-lang.org>
> > Sent: Thursday, August 26, 2010 12:51:58 PM GMT -05:00 US/Canada 
> > Eastern
> > Subject: [racket] problem with map example in docs of typed/racket
> > 
> > 
> > 
> > See below,
> > Jos
> > 
> > In definitions window
> > 
> > #lang typed/racket
> > (: map
> > (All (C A B ...)
> > ((A B ... B -> C) (Listof A) (Listof B) ... B
> > -> 
> > (Listof C))))
> > (define (map f as . bss)
> > (if (or (null? as)
> > (ormap null? bss))
> > null
> > (cons (apply f (car as) (map car bss)) ; These to lines 
> (apply map f 
> > (cdr as) (map cdr bss))))) ; are highlighted
> > 
> > Run, then in interactions window: 
> > 
> > 
> > Welcome to DrRacket, version
> > 
> 5.0.1.3--2010-08-19(e55f0cade1d47b2edbc65e7dd61ddce2041814af/a) [3m]. 
> > Language: typed/racket. 
> > . Type Checker: Polymorphic function map could not be applied to 
> > arguments:
> > Domain: (A B ... B -> C) (Listof A) (Listof B) ... B
> > Arguments: (All (a b) (case-lambda ((Pairof a b) -> a) 
> ((Listof a) -> 
> > a))) (List (Listof B) ... B)
> > in: (map car bss)
> > . Type Checker: Bad arguments to function in apply: 
> > Domain: A B ... B
> > Arguments: A Nothing *
> > in: (apply f (car as) (map car bss))
> > . Type Checker: Polymorphic function map could not be applied to 
> > arguments:
> > Domain: (A B ... B -> C) (Listof A) (Listof B) ... B
> > Arguments: (All (a b) (case-lambda ((Pairof a b) -> b) 
> ((Listof a) -> 
> > (Listof a)))) (List (Listof B) ... B)
> > in: (map cdr bss)
> > . Type Checker: Bad arguments to polymorphic function in apply: 
> > Domain: (A B ... B -> C) (Listof A) (Listof B) ... B
> > Arguments: (A B ... B -> C) (Listof A) Nothing *
> > in: (apply map f (cdr as) (map cdr bss)) . Type Checker: 
> > Summary: 4 errors encountered in: 
> > (map car bss)
> > (apply f (car as) (map car bss))
> > (map cdr bss)
> > (apply map f (cdr as) (map cdr bss))
> > > 
> > 
> > 
> > 
> > 
> > 
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