[racket] Typed racket and command line parameters

The first thing I notice is that opt-max-size is a (Parameterof Any), but you use string->number on it.  
So you should probably put a guard on the opt-max-size parameter something like this:
(: opt-max-size (Parameterof Any Real))
(: opt-max-size-guard (Any -> Real))
(define (opt-max-size-guard val)
  (cond [(real? val) val]
        [(string? val) (opt-max-size-guard (string->number val))]
        [else (error "Max size: must be a real number")]))

(define opt-max-size (make-parameter 0 opt-max-size-guard))

On Jun 21, 2014, at 3:45 AM, Manfred Lotz <manfred.lotz at arcor.de> wrote:

> Hi there,
> I try to change one of my programs to typed racket and fail because of
> errors when dealing with command line arguments.
> 
> Here a minimum example:
> 
> #lang typed/racket/base
> 
> (require racket/cmdline)
> 
> 
> (: opt-verbose-mode (Parameterof Boolean))
> (define opt-verbose-mode (make-parameter #f))
> (: opt-max-size (Parameterof Any))
> (define opt-max-size (make-parameter "0"))
> 
> 
> 
> (define parms
>  (command-line
>   #:program "mypgm"
>   #:once-each
>   [("-v" "--verbose") "Show verbose output" (opt-verbose-mode #t)]
>   [("-m" "--max-size") NUM ("Max size." "NUM") (opt-max-size NUM) ]
>   ))
> 
> 
> (define (myfun)
>  (when (opt-verbose-mode)
>    (if (> (string->number (opt-max-size)) 0)
>        #t
>        #f)))
> 
> 
> What do I do wrong? Any hint appreciated.
> 
> -- 
> Thanks,
> Manfred
> 
> 
> 
> 
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