Oh! Really. Thank you! Sorry, I am not experienced in Racket.
2014-10-02 0:56 GMT+04:00 Matthias Felleisen <matth...@ccs.neu.edu>: > > 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....@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 > > > > ____________________ > > Racket Users list: > > http://lists.racket-lang.org/users > > -- Best regards, Yuri
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