[racket] enter! not working?
Are you working with the `racket' command-line program or within
DrRacket?
Within DrRacket, you don't need `enter!'.
At Sun, 27 Jun 2010 22:06:52 +1000, "Brad Long" wrote:
> I am using DrRacket Version 5 on Windows. When I follow the example (see
> below) and get to the part where I am suppposed to use "enter!", I get this
> error:
>
> reference to an identifier before its definition: enter!
>
> Thanks for any help.
>
> Brad.
>
> ===> START
>
> #lang racket
>
> (define (extract str)
> (substring str 4 7))
>
> If calling (extract "the boy") is part of the main action of your program,
> that would go in the definitions area, too. But if it was just an example
> expression that you were using to explore extract, then you'd more likely
> leave the definitions area as above, click Run, and then evaluate (extract
> "the boy") in the REPL.
>
> With racket, you'd save the above text in a file using your favorite editor.
> If you save it as "extract.rkt", then after starting racket in the same
> directory, you'd evaluate the following sequence:
>
> > (enter! "extract.rkt")
> > (extract "the gal out of the city")
>
> "gal"
>
> The enter! form both loads the code and switches the evaluation context to
> the inside of the module, just like DrRacket's Run button.
>
> =====> END
>
>
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