On Sat, May 09, 2020 at 12:24:16PM -0400, Ben Greenman wrote: > On 5/9/20, Hendrik Boom <[email protected]> wrote: > > I get the message > > > > readspec.rkt:195:8: Type Checker: Expression should produce 3 values, but > > produces 1 values of types String in: (for/set : (Setof String) (((l : > > String) (cast (in-lines input-port) (Sequenceof String)))) (cast > > (string-trim l) String)) > > > > from the following function: > > > > (define (read-manpages [input-port : Input-Port]) > > (cast (for/set : (Setof String) (([l : String] (cast (in-lines input-port) > > (Sequenceof String)))) > > (cast (string-trim l) String)) > > (Setof String))) > > > > The expression it is complaining about is the (for/list ......) > > construction. > > > > I'm trying to covert a Racket program to a typed Racket program. > > As far as I can see, this function reads words, one to a line, from > > input-port and makes a set of these words. > > > > It baffles me where the type checker gets the idea that 3 values are wanted > > > > anywhere. > > > > I put in a lot of casts just to make sure I knew what types it had to work > > with. > > > > The original code, without types: > > > > (define (read-manpages input-port) > > (for/set ((l (in-lines input-port))) > > (string-trim l))) > > > > Any ideas? > > Well this is unfortunate. > > `(l : String)` should be `l : String` with no parentheses
Got it. It's confusing whenyuo need the parentheses around a type-binding and when you don't. -- hendrik > > The code you have looks like this to Typed Racket: > > ``` > (for/set : TYPE > (((val0 val1 val2) (in-lines input-port))) > LOOP-BODY) > ``` > > -- > 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 [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/racket-users/CAFUu9R7wBS_hbZpXmFR097qxi8F-54rkogEXe6R0Nyqp_iMqDQ%40mail.gmail.com. -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/20200509181040.iwzvd4un2btgcf4w%40topoi.pooq.com.
