[racket] strange behaviour of a (match) form

In this context, null is just a variable and it gets bound to what it matches: 

> Welcome to Racket v6.1.0.8.
> > (match 'hello-world [null null])
> 'hello-world



On Oct 1, 2014, at 4:52 PM, Yuri Garmay <yuri.from.spb at gmail.com> wrote:

> Hi, all
> 
> Accidentally, I found out that null matchs in unexpected way (seems it matchs always) 
> 
> So,
> (define (length-my list)
>   (match list
>     ['() 0]
>     [(cons x xs)
>      (+ 1
>         (length-my xs))]
>     [_ 'not-a-list]))
> (length-my '(1 2 3 4))
> >produces 4
> 
> But
> (define (length-my list)
>   (match list
>     [null 0]
>     [(cons x xs)
>      (+ 1
>         (length-my xs))]
>     [_ 'not-a-list]))
> (length-my '(1 2 3 4))
> >produces 0
> 
> I also tried that:
> (match '213423
>   [null 0]
>   [_ 1])
> >produces 0
> (match null
>   ['213423 0]
>   [_ 1])
> >produces 1
> 
> Is it a bug?
> 
> I am using Racket 6.1
> 
> -- 
> Best regards,
> Yuri
> 
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