[racket] Typed Racket Performance Optimization

From: Vincent St-Amour (stamourv at ccs.neu.edu)
Date: Thu May 10 08:38:04 EDT 2012

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.


At Wed, 9 May 2012 23:52:42 -0400,
Ray Racine wrote:
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> 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?))
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