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Make the whole text fit in 70 characters.
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Eli Barzilay 2013-07-16 02:03:51 -04:00
parent 6af5c957d0
commit e39faf7019
1 changed files with 18 additions and 12 deletions
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@ -73,7 +73,7 @@ Feedback is appreciated! You can reach me at [@th3rac25](http://twitter.com/th3r
"Hello, world!"
"Benjamin \"Bugsy\" Siegel" ; backslash is an escaping character
"Foo\tbar\41\x21\u0021\a\r\n" ; includes C escapes, Unicode
"λx:(μα.α→α).xx" ; any Unicode character can appear in a string constant
"λx:(μα.α→α).xx" ; can include Unicode characters
;; Strings can be added too!
(string-append "Hello " "world!") ; => "Hello world!"
@ -267,8 +267,8 @@ m ; => '#hash((b . 2) (a . 1) (c . 3)) <-- no `d'
; => "this is true"
;; In conditionals, all non-#f values are treated as true
(member "Groucho" '("Harpo" "Groucho" "Zeppo")) ; => '("Groucho" "Zeppo")
(if (member "Groucho" '("Harpo" "Groucho" "Zeppo"))
(member 'Groucho '(Harpo Groucho Zeppo)) ; => '(Groucho Zeppo)
(if (member 'Groucho '(Harpo Groucho Zeppo))
'yep
'nope)
; => 'yep
@ -315,7 +315,8 @@ m ; => '#hash((b . 2) (a . 1) (c . 3)) <-- no `d'
i) ; => '(2)
(for/hash ([i '(1 2 3)])
(values i (number->string i))) ; => '#hash((1 . "1") (2 . "2") (3 . "3"))
(values i (number->string i)))
; => '#hash((1 . "1") (2 . "2") (3 . "3"))
;; To combine iteration results, use `for/fold'
(for/fold ([sum 0]) ([i '(1 2 3 4)])
@ -371,9 +372,11 @@ vec ; => #(1 2 3 4)
;; 7. Modules
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Modules let you organize code into multiple files and reusable libraries
;; Modules let you organize code into multiple files and reusable
;; libraries; here we use sub-modules, nested in the whole module that
;; this text makes (starting from the "#lang" line)
(module cake racket/base ; define a new module 'cake' based on racket/base
(module cake racket/base ; define a `cake' module based on racket/base
(provide print-cake) ; function exported by the module
@ -404,9 +407,12 @@ vec ; => #(1 2 3 4)
;; Field
(define current-size size)
;; Public methods
(define/public (get-size) current-size)
(define/public (grow amt) (set! current-size (+ amt current-size)))
(define/public (eat other-fish) (grow (send other-fish get-size)))))
(define/public (get-size)
current-size)
(define/public (grow amt)
(set! current-size (+ amt current-size)))
(define/public (eat other-fish)
(grow (send other-fish get-size)))))
;; Create an instance of fish%
(define charlie
@ -444,7 +450,7 @@ vec ; => #(1 2 3 4)
(define a 2)
(define b 3)
(swap a b)
(printf "tmp = ~a; a = ~a; b = ~a\n" tmp a b) ; tmp is unaffected by swap
(printf "tmp = ~a; a = ~a; b = ~a\n" tmp a b) ; tmp is unaffected
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; 10. Contracts
@ -454,7 +460,7 @@ vec ; => #(1 2 3 4)
(module bank-account racket
(provide (contract-out
[deposit (-> positive? any)] ; amount will always be a positive number
[deposit (-> positive? any)] ; amounts are always positive
[balance (-> positive?)]))
(define amount 0)
@ -467,7 +473,7 @@ vec ; => #(1 2 3 4)
(balance) ; => 5
;; Any client that attempt to deposit a non-positive amount, will be blamed
;; Clients that attempt to deposit a non-positive amount are blamed
;; (deposit -5) ; => deposit: contract violation
;; expected: positive?
;; given: -5