It was late... but the penny dropped this morning. Consider the domain of log (x) for x<0.
On Thu, May 10, 2012 at 8:38 AM, Vincent St-Amour <stamo...@ccs.neu.edu>wrote: > As Neil said, `fllog' is guaranteed to return floats. > > If you want to know for which input types `log' has a return type of > `Float', you can use `:query-result-type' at the TR REPL. > > -> (:query-result-type log Float) > (case-> (Nonnegative-Flonum -> Float) (Float-Zero -> Negative-Float)) > > If you can't restrict the input type, the solution you mention (adding a > runtime assertion) is perfectly fine, but does involve a check at runtime. > > Vincent > > > At Wed, 9 May 2012 23:52:42 -0400, > Ray Racine wrote: > > > > [1 <multipart/alternative (7bit)>] > > [1.1 <text/plain; ISO-8859-1 (7bit)>] > > The Typed Racket Performance button in DrRacket informs me that (log v) > > returns a Complex type, despite all its arguments being reals and that > if I > > do not want or expect a complex number as results, I mam restrict the > type > > of the arguments. How does one do that? > > > > #lang typed/racket/base > > > > (: real-log (Float -> Float)) > > (define (real-log v) > > (assert (log v) flonum?)) > > [1.2 <text/html; ISO-8859-1 (quoted-printable)>] > > > > [2 <text/plain; us-ascii (7bit)>] > > ____________________ > > Racket Users list: > > http://lists.racket-lang.org/users >
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