[racket] on-key question

Hello,

I have to make a function which do nothing with the special key's.
According to the manual I can use this :


Here is a typical key-event handler:

    (define
    <http://docs.racket-lang.org/reference/define.html?q=on-key#%28form._%28%28lib._racket/private/base..rkt%29._define%29%29>(changewa-key)

    (cond
    <http://docs.racket-lang.org/reference/if.html?q=on-key#%28form._%28%28lib._racket/private/letstx-scheme..rkt%29._cond%29%29>

    [(key=?
    <http://docs.racket-lang.org/teachpack/2htdpuniverse.html?q=on-key#%28def._%28%28lib._2htdp/universe..rkt%29._key%7E3d%7E3f%29%29>a-key"left")(world-gow-DELTA)]

    [(key=?
    <http://docs.racket-lang.org/teachpack/2htdpuniverse.html?q=on-key#%28def._%28%28lib._2htdp/universe..rkt%29._key%7E3d%7E3f%29%29>a-key"right")(world-gow+DELTA)]

    [(=
    <http://docs.racket-lang.org/reference/generic-numbers.html?q=on-key#%28def._%28%28quote._%7E23%7E25kernel%29._%7E3d%29%29>(string-length
    <http://docs.racket-lang.org/reference/strings.html?q=on-key#%28def._%28%28quote._%7E23%7E25kernel%29._string-length%29%29>a-key)1)w];order-free
    checking
    [(key=?
    <http://docs.racket-lang.org/teachpack/2htdpuniverse.html?q=on-key#%28def._%28%28lib._2htdp/universe..rkt%29._key%7E3d%7E3f%29%29>a-key"up")(world-gow-DELTA)]

    [(key=?
    <http://docs.racket-lang.org/teachpack/2htdpuniverse.html?q=on-key#%28def._%28%28lib._2htdp/universe..rkt%29._key%7E3d%7E3f%29%29>a-key"down")(world-gow+DELTA)]

    [else
    <http://docs.racket-lang.org/reference/if.html?q=on-key#%28form._%28%28lib._racket/private/letstx-scheme..rkt%29._else%29%29>w]))




But Can I use this if I want that if a special-key is used nothing happens.


[key?a-key "/t") ()]

Roelof

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