At Thu, 13 Feb 2014 14:45:08 -0500, Bloch Stephen wrote: > Don't tell me the Zero I'm running into is the initial value of > for/sum's hidden accumulator....
Yes, that's where the Zero comes from. > And even if there were a zero, shouldn't Zero be a subtype of Flonum? Zero is the type of the exact integer 0, but the Flonum type only includes floating-point numbers. The two are not related by subtyping. You can use `assert' to check, at run-time, that you do always get a Flonum: (assert (for/sum: : Real [[ii : Index 300]] pi) flonum?) This expression typechecks at type Flonum. Vincent ____________________ Racket Users list: http://lists.racket-lang.org/users