Documented TR's behavior when mixing exactness.

original commit: cf692e986d2a3690260884d929daae321d21eeb3
This commit is contained in:
Vincent St-Amour 2010-08-11 20:00:01 -04:00
parent f9b3146577
commit f2b9a8fe2c

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@ -58,6 +58,14 @@ Thus, to get the most of Typed Racket's optimizer, you should use the
floating-point literals instead of exact literals when doing
floating-point computations.
When mixing floating-point numbers and exact reals in arithmetic
operations, the result is not necessarily a @racket[Float]. For
instance, the result of @racket[(* 2.0 0)] is @racket[0] which is not
a @racket[Float]. This can result in missed optimizations. To prevent
this, when mixing floating-point numbers and exact reals, coerce exact
reals to floating-point numbers using @racket[exact->inexact]. This is
not necessary when using @racket[+] or @racket[-].
On a similar note, the @racket[Inexact-Complex] type is preferable to
the @racket[Complex] type for the same reason. Typed Racket can keep
@tech[#:doc '(lib "scribblings/reference/reference.scrbl") #:key