On Tue, Jul 26, 2011 at 11:37 PM, Niitsuma Hirotaka
<[email protected]> wrote:
> more problem
>
> It happen on linux
>
> save as a.scm
> ---------
> (display (+ 10 3))
> ---------
> then call from shell
>
> $ racket -f a.scm
> 13
>
> It works OK
But just as a note: this use of Racket is not as popular these days,
because the file above is not a "module". In idiomatic Racket, I
would translate the above to a file called 'a.rkt' with the content:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
#lang racket
(display (+ 10 3))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
The lang line at the top of the file explicitly labels the program as
one written in "racket". The file can be executed from the shell with
the following:
$ racket a.rkt
I would stay away from non-module code in Racket unless I had a very
good reason to do so. Modules do a good amount of error trapping. If
I misspell an identifier in a function definition, for example,
modules will catch the errors at compile time, rather than at run
time. As an example, I can try to compile:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
#lang racket
(define (greet name)
(string-append "hello " nme))
(greet "Niitsuma")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
If I write this as a module, then Racket will tell me immediately that
I've misspelled 'nme'.
But if I were to do the same without modules, by having a file without
the lang line and running it with -f, Racket will try to look up the
value of 'nme' at runtime at the toplevel, which is almost certainly
not what I want.
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