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Show a REPL type printing example in the TR guide

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Please merge to v6.0.1
(cherry picked from commit 52cc507aa5)
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Asumu Takikawa 2014-04-07 21:20:14 -04:00 committed by Ryan Culpepper
parent 74f82bbd1d
commit e70b606142
1 changed files with 14 additions and 3 deletions
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17
pkgs/typed-racket-pkgs/typed-racket-doc/typed-racket/scribblings/guide/begin.scrbl
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@ -23,7 +23,7 @@ are provided as well; for example, the
@racketmodname[typed/racket/base] language corresponds to
@racketmodname[racket/base].
@racketblock[(struct: pt ([x : Real] [y : Real]))]
@racketblock+eval[#:eval the-eval (struct: pt ([x : Real] [y : Real]))]
@margin-note{Many forms in Typed Racket have the same name as the
untyped forms, with a @racket[:] suffix.}
@ -36,7 +36,7 @@ form from @racketmodname[racket]---when porting a program from
@racketmodname[racket] to @racketmodname[typed/racket], uses of
@racket[struct] should be changed to @racket[struct:].
@racketblock[(: distance (-> pt pt Real))]
@racketblock+eval[#:eval the-eval (: distance (-> pt pt Real))]
This declares that @racket[distance] has the type @racket[(-> pt pt Real)].
@;{@racket[distance] must be defined at the top-level of the module containing
@ -52,7 +52,7 @@ function type, in this case @racket[Real].
If you are familiar with @rtech{contracts}, the notation for function
types is similar to function contract combinators.
@racketblock[
@racketblock+eval[#:eval the-eval
(define (distance p1 p2)
(sqrt (+ (sqr (- (pt-x p2) (pt-x p1)))
(sqr (- (pt-y p2) (pt-y p1))))))
@ -66,6 +66,17 @@ the function has the type @racket[Real], under the assumption that
from the earlier type declaration. Since the body does have this type,
the program is accepted.
In the Typed Racket @gtech{REPL}, calling @racket[distance] will
show the result as usual and will also print the result's type:
@interaction[#:eval the-eval (distance (pt 0 0) (pt 3.1415 2.7172))]
Just evaluating the function name will print the function value and its type,
which can be useful for discovering the types that Typed Racket ascribes to
Racket functions. Alternatively, the @racket[:print-type] command will just
print the type:
@interaction[#:eval the-eval distance string-length (:print-type string-ref)]
@section{Datatypes and Unions}