This is a known issue: plot-pict does not return a typed/pict type · Issue #15 · racket/plot (github.com) <https://github.com/racket/plot/issues/15>
Alex. On Tuesday, November 24, 2020 at 7:24:17 PM UTC+8 tim wrote: > Hi everyone, > > In typed racket, vc-append expects arguments of type pict, while plot-pict > produces results of type Pict. Therefore, to have vc-append accept a > plot-pict argument, I’m currently casting the result of plot-pict to be > of type pict. > > From my understanding of the underlying racket code, Pict just invokes a > pict? predicate through an #opaque definition, and cast inserts a runtime > test of its argument. Therefore, my cast seems wasteful. Have I missed > something? Is there a better way to structure a solution that type-checks? > > Here’s some code that type-checks for me: > > #lang typed/racket > > (require plot > pict) > > (vc-append (cast (plot-pict (function sin 0 1)) > pict)) > > > and the output is a graph, as expected. > > Here’s some that fails a type-check: > > #lang typed/racket > > (require plot > pict) > > (vc-append (plot-pict (function sin 0 1))) > > > Error output: > > ; plot-pict-test.rkt:6:11: Type Checker: type mismatch > ; expected: pict > ; given: Pict > ; in: (plot-pict (function sin 0 1)) > ; Context (plain; to see better errortrace context, re-run with C-u > prefix): > ; > /Applications/Racket/share/pkgs/typed-racket-lib/typed-racket/typecheck/tc-toplevel.rkt:376:0 > > type-check > ; > /Applications/Racket/share/pkgs/typed-racket-lib/typed-racket/typecheck/tc-toplevel.rkt:619:0 > > tc-module > ; > /Applications/Racket/share/pkgs/typed-racket-lib/typed-racket/tc-setup.rkt:96:12 > ; > /Applications/Racket/share/pkgs/typed-racket-lib/typed-racket/typed-racket.rkt:23:4 > > I get the same results whether I require pict or typed/pict. > > I hope this question is of general interest. I have some familiarity with > regular racket, but I’m only just starting out on typed racket. > > Best, > > > > Tim > > -- 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/91d1094d-fe0a-46a9-9fc7-21355dea7163n%40googlegroups.com.
