From d614c6eea0a261b103d2380f826b43cdb6be1757 Mon Sep 17 00:00:00 2001 From: Asumu Takikawa Date: Fri, 12 Sep 2014 16:53:45 -0400 Subject: [PATCH] Fix TR reference discussion of filters Thanks to Anthony Carrico original commit: 290cc2dd7e02a023c2ed4b13827b98d2025a99fe --- .../typed-racket/scribblings/reference/types.scrbl | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/pkgs/typed-racket-pkgs/typed-racket-doc/typed-racket/scribblings/reference/types.scrbl b/pkgs/typed-racket-pkgs/typed-racket-doc/typed-racket/scribblings/reference/types.scrbl index a6a1aca0..a70399a2 100644 --- a/pkgs/typed-racket-pkgs/typed-racket-doc/typed-racket/scribblings/reference/types.scrbl +++ b/pkgs/typed-racket-pkgs/typed-racket-doc/typed-racket/scribblings/reference/types.scrbl @@ -613,9 +613,10 @@ functions and continuation mark functions. @ex[string?] - The filter specifies that when @racket[(string? x)] evaluates to a true value, the - variable @racket[x] can be assumed to have type @racket[String]. Likewise, if the - expression evaluates to @racket[#f], the variable has type @racket[String]. + The filter specifies that when @racket[(string? x)] evaluates to a true value for + a conditional branch, the variable @racket[x] in that branch can be assumed to have + type @racket[String]. Likewise, if the expression evaluates to @racket[#f] in a branch, + the variable @emph{does not} have type @racket[String]. In some cases, asymmetric type information is useful in filters. For example, the @racket[filter] function's first argument is specified with only a positive filter: