Awesome. Thanks! Where can I find the documentation for this TR reader syntax?
Why is TR not able to figure out the type for these variables without human
help? Does that mean the implementation of `command-line` is in TR and the
types of those variables are inferred by the type system, or they are
explicitly typed to be `Any` for simplicity?
On Monday, March 6, 2017 at 2:48:15 PM UTC-8, Sam Tobin-Hochstadt wrote:
> You can use the #{x : T} reader syntax to annotate variables in macros
> like `command-line`. Here's a working version of your code:
>
> ```
> #lang typed/racket
>
> (define *channel* (make-parameter "#general"))
> (define *message* : (Parameterof (Listof String)) (make-parameter '()))
>
>
> (define (parse-cmdline)
> (command-line
> #:program "q"
> #:once-each
> [("-c" "--channel") #{ch : String} "slack channel to post (default:
> use .qrc setting or default)" (*channel* ch)]
> #:args #{msg : String}
> (*message* msg)))
> ```
>
> On Mon, Mar 6, 2017 at 2:08 AM, kay <> wrote:
> > For a complex syntax form like `command-line`, I have difficulty correctly
> > annotate the bindings it defines.
> >
> > More specifically, in the below code, for variable `msg`, even the
> > document[1] says the `#:args` binds as list of **strings**, but the error
> > indicates that it somehow is declared as `Listof Any`.
> >
> > Similarly, for variable `ch` bound in line 11, I believe it should always
> > be `String`, but it somehow is declared to be `Any`.
> >
> > What should I do with this type of error, if I want my varaibles to be more
> > precisely typed than just `Any`?
> >
> >
> > [1]:
> > https://docs.racket-lang.org/reference/Command-Line_Parsing.html?q=command-line#%28form._%28%28lib._racket%2Fcmdline..rkt%29._command-line%29%29
> >
> > ```
> > 1 #lang typed/racket
> > 2
> > 3 (define *channel* (make-parameter "#general"))
> > 4 (define *message* : (Parameterof (Listof String)) (make-parameter
> > '()))
> > 5
> > 6
> > 7 (define (parse-cmdline)
> > 8 (command-line
> > 9 #:program "q"
> > 10 #:once-each
> > 11 [("-c" "--channel") ch "slack channel to post (default: use
> > .qrc setting or default)" (*channel* ch)]
> > 12 #:args msg
> > 13 (*message* msg)))
> > 14
> > 15
> > 16 #|
> > 17 tr.rkt:11:91: Type Checker: Wrong argument to parameter - expected
> > String and got Any in: (*channel* ch)
> > 18 tr.rkt:13:5: Type Checker: Wrong argument to parameter - expected
> > (Listof String) and got (Listof Any) in: (*message* msg)
> > 19 |#
> > ```
> >
> > --
> > 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 [email protected].
> > For more options, visit https://groups.google.com/d/optout.
--
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 [email protected].
For more options, visit https://groups.google.com/d/optout.
