Does using andmap with the custom predicates you alluded to for that union you mentioned work?
Something like this perhaps?: #lang typed/racket (struct: T1 ()) (struct: T2 ()) (define-type T1or2 (U T1 T2)) (: T1or2? (-> Any Boolean : T1or2)) (define (T1or2? a) (or (T1? a) (T2? a))) (: listof-T1or2 (-> Any Boolean : (Listof T1or2))) (define (listof-T1or2 l) (and (list? l) (andmap T1or2? l))) On Fri, Sep 26, 2014 at 12:28 PM, Konrad Hinsen <konrad.hin...@fastmail.net> wrote: > Andrew Kent writes: > > > Will andmap work for you? > > Interesting... I didn't know about that one. > > For my demonstration code, that's indeed a good solution. In my real > application, the test is more complicated. I need to check all > elements of a list for conformance to a union type, so I have no > prefabricated predicate, not even for the elements of my list. > > Konrad. > ____________________ > Racket Users list: > http://lists.racket-lang.org/users >
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