On 3/30/20, Aron Zvi <aron...@gmail.com> wrote: > Hey guys > > In 22.3 Domain-Specific Languages: Configurations, the book introduces the > following data example and data definitions for FSM configurations > > > (define > <http://docs.racket-lang.org/htdp-langs/intermediate-lam.html#%28form._%28%28lib._lang%2Fhtdp-intermediate-lambda..rkt%29._define%29%29> > xm0 > '(machine ((initial "red")) > (action ((state "red") (next "green"))) > (action ((state "green") (next "yellow"))) > (action ((state "yellow") (next "red"))))) > > ; An XMachine is a nested list of this shape: > ; `(machine ((initial ,FSM-State > <https://www.htdp.org/2019-02-24/part_two.html#%28tech._fsm._state%29>)) [ > List-of > <https://www.htdp.org/2019-02-24/part_three.html#%28tech._sim-dd._list._of%29> > > X1T <https://www.htdp.org/2019-02-24/part_four.html#%28tech._x1t%29>]) > ; An X1T is a nested list of this shape: > ; `(action ((state ,FSM-State > <https://www.htdp.org/2019-02-24/part_two.html#%28tech._fsm._state%29>) ( > next ,FSM-State > <https://www.htdp.org/2019-02-24/part_two.html#%28tech._fsm._state%29>))) > I do no understand the XMachine data definition properly. In the definition > > it appears that it would be a list with 3 elements: > > 1*. *'machine > 2. `((initial ,FSM-State > <https://www.htdp.org/2019-02-24/part_two.html#%28tech._fsm._state%29>)) > 3. [List-of > <https://www.htdp.org/2019-02-24/part_three.html#%28tech._sim-dd._list._of%29> > > X1T <https://www.htdp.org/2019-02-24/part_four.html#%28tech._x1t%29>] > > However, from the data example (and the fact that it is an Xexpr > <https://www.htdp.org/2019-02-24/part_four.html#%28tech._xexpr%29>) I know > that the intention is different and that it is a list of the form: > > 1. 'machine > 2. `((initial ,FSM-State > <https://www.htdp.org/2019-02-24/part_two.html#%28tech._fsm._state%29>)) > 3. X1T <https://www.htdp.org/2019-02-24/part_four.html#%28tech._x1t%29>-1 > ... > X1T <https://www.htdp.org/2019-02-24/part_four.html#%28tech._x1t%29>-n > > where is seems that [List-of > <https://www.htdp.org/2019-02-24/part_three.html#%28tech._sim-dd._list._of%29> > > X1T <https://www.htdp.org/2019-02-24/part_four.html#%28tech._x1t%29>]is > expanded and included in the list ([List-of > <https://www.htdp.org/2019-02-24/part_three.html#%28tech._sim-dd._list._of%29> > X1T <https://www.htdp.org/2019-02-24/part_four.html#%28tech._x1t%29>] is > consed > onto) > > Can you please explain how the given `(machine ((initial ,FSM-State > <https://www.htdp.org/2019-02-24/part_two.html#%28tech._fsm._state%29>)) [ > List-of > <https://www.htdp.org/2019-02-24/part_three.html#%28tech._sim-dd._list._of%29> > > X1T <https://www.htdp.org/2019-02-24/part_four.html#%28tech._x1t%29>]) > translates > to this? >
I think you are right. An XMachine should be a list of 3 elements by that data definition. The definition should probably have a "." (or use `cons`es): `(machine ((initial ,FSM-State)) . [List-of X1T]) -- 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 racket-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/CAFUu9R7z4NZMpvRmNMqFsgxoaWQReZDokS19E4o60GJX8rye-Q%40mail.gmail.com.
