Beau­tiful Racket / explainers

1. 

   In your terminal window, by launching racket:

   

   ~ : racket
   Welcome to Racket v8.5.0.2.
   -> (* 6 7)
   42
   -> (current-milliseconds)
   -> 1715634826768
   -> (define xyzzy (random 100))
   -> xyzzy
   83

   1 2 3 4 5 6 7 8 9

   ~ : racket Welcome to Racket v8.5.0.2. -> (* 6 7) 42 -> (current-milliseconds) -> 1715634826768 -> (define xyzzy (random 100)) -> xyzzy 83

   
   

   You can specify a different language for this repl with the -I flag:

   

   ~ : racket -I br
   Welcome to Racket v8.5.0.2.
   -> (define-macro (foo THIS) #'42)
   -> (foo "you")
   42

   1 2 3 4 5

   ~ : racket -I br Welcome to Racket v8.5.0.2. -> (define-macro (foo THIS) #'42) -> (foo "you") 42

   
2. 

   You can also access the REPL in DrRacket, by using the prompt in the inter­ac­tions panel:

   

   Welcome to DrRacket, version 8.5.0.2 [3m].
   Language: racket [custom]; memory limit: 3000 MB.
   (* 6 7)
   42
   >

   1 2 3 4 5

   Welcome to DrRacket, version 8.5.0.2 [3m]. Language: racket [custom]; memory limit: 3000 MB. > (* 6 7) 42 >

   
   

   Unlike the command-line REPL, the DrRacket REPL adopts the language spec­i­fied by the #lang line at the top of the defi­n­i­tions panel. DrRacket also uses the REPL itself to print output from the program.

   

   The DrRacket REPL lets you use vari­ables and func­tions from the source file in the defi­n­i­tions window (even if they’re not made avail­able through provide). So if this is the program:

   

   (define foo "bar")
   (define (repeat str) (string-append str str))

   1 2	(define foo "bar") (define (repeat str) (string-append str str))

   
   

   After you run the file (to update the defi­n­i­tions), you can use them at the DrRacket REPL:

   

   Welcome to DrRacket, version 8.5.0.2 [3m].
   Language: br [custom]; memory limit: 3000 MB.
   foo
   "bar"
   (repeat foo)
   "barbar"
   >

   1 2 3 4 5 6 7

   Welcome to DrRacket, version 8.5.0.2 [3m]. Language: br [custom]; memory limit: 3000 MB. > foo "bar" > (repeat foo) "barbar" >

   
   

   Textual output is just the begin­ning of the DrRacket REPL. It can display a range of data formats, including images and inter­ac­tive plots.

• 

  Other command-line options for racket in the Racket Refer­ence

• 

  The inter­ac­tions window in the DrRacket docs