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authorEli Barzilay <eli@barzilay.org>2013-07-16 01:22:11 -0400
committerEli Barzilay <eli@barzilay.org>2013-07-16 01:22:11 -0400
commit4ad1441e839282f97fc3e2031f97a4adc552a707 (patch)
treea7d0b2867f1f0d7a348faf85ccdf0538c8912c59
parent4718ea4e0cbd26c5ad36d67bc73e3b8192370169 (diff)
Normalize top comments to start with ";;".
Leave a single ";" for commented expressions and output indications.
-rw-r--r--racket.html.markdown155
1 files changed, 77 insertions, 78 deletions
diff --git a/racket.html.markdown b/racket.html.markdown
index 4b72591a..25b92f62 100644
--- a/racket.html.markdown
+++ b/racket.html.markdown
@@ -17,7 +17,7 @@ Feedback is appreciated! You can reach me at [@th3rac25](http://twitter.com/th3r
;;; Comments
-; Single line comments start with a semicolon
+;; Single line comments start with a semicolon
#| Block comments
can span multiple lines and...
@@ -26,7 +26,7 @@ Feedback is appreciated! You can reach me at [@th3rac25](http://twitter.com/th3r
|#
|#
-; S-expression comments discard the following expression
+;; S-expression comments discard the following expression
#; "this expression will be discarded" "2nd expression" ; => "2nd expression"
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -40,12 +40,12 @@ Feedback is appreciated! You can reach me at [@th3rac25](http://twitter.com/th3r
1/2 ; rationals
1+2i ; complex numbers
-; Function application is written (f x y z ...)
-; where f is a function and x, y, z, ... are operands
-; If you want to create a literal list of data, use ' to stop it from
-; being evaluated
+;; Function application is written (f x y z ...)
+;; where f is a function and x, y, z, ... are operands
+;; If you want to create a literal list of data, use ' to stop it from
+;; being evaluated
'(+ 1 2) ; => (+ 1 2)
-; Now, some arithmetic operations
+;; Now, some arithmetic operations
(+ 1 1) ; => 2
(- 8 1) ; => 7
(* 10 2) ; => 20
@@ -73,34 +73,34 @@ Feedback is appreciated! You can reach me at [@th3rac25](http://twitter.com/th3r
"Benjamin \"Bugsy\" Siegel" ; backslash is an escaping character
"λx:(μα.α→α).xx" ; any Unicode character can appear in a string constant
-; Strings can be added too!
+;; Strings can be added too!
(string-append "Hello " "world!") ; => "Hello world!"
-; A string can be treated like a list of characters
+;; A string can be treated like a list of characters
(string-ref "Apple" 0) ; => #\A
-; format can be used to format strings:
+;; format can be used to format strings:
(format "~a can be ~a" "strings" "formatted")
-; Printing is pretty easy
+;; Printing is pretty easy
(printf "I'm Racket. Nice to meet you!\n")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; 2. Variables
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-; You can create a variable using define
-; a variable name can use any character except: ()[]{}",'`;#|\
+;; You can create a variable using define
+;; a variable name can use any character except: ()[]{}",'`;#|\
(define some-var 5)
some-var ; => 5
-; You can also use unicode characters
+;; You can also use unicode characters
(define ⊆ subset?)
(⊆ (set 3 2) (set 1 2 3)); => #t
-; Accessing a previously unassigned variable is an exception
-;x ; => x: undefined ...
+;; Accessing a previously unassigned variable is an exception
+; x ; => x: undefined ...
-; Local binding: me is bound to "Bob" only within (let ...)
+;; Local binding: me is bound to "Bob" only within (let ...)
(let ([me "Bob"])
"Alice"
me) ; => "Bob"
@@ -109,7 +109,7 @@ some-var ; => 5
;; 3. Structs and Collections
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-; Structs
+;; Structs
(struct dog (name breed age))
(define my-pet
(dog "lassie" "collie" 5))
@@ -118,95 +118,95 @@ my-pet ; => #<dog>
(dog-name my-pet) ; => "lassie"
;;; Pairs (immutable)
-; "cons" constructs pairs, "car" and "cdr" extract the first
-; and second elements
+;; "cons" constructs pairs, "car" and "cdr" extract the first
+;; and second elements
(cons 1 2) ; => '(1 . 2)
(car (cons 1 2)) ; => 1
(cdr (cons 1 2)) ; => 2
;;; Lists
-; Lists are linked-list data structures
+;; Lists are linked-list data structures
(list 1 2 3) ; => '(1 2 3)
-; Use "cons" to add an item to the beginning of a list
+;; Use "cons" to add an item to the beginning of a list
(cons 4 '(1 2 3)) ; => (4 1 2 3)
-; Use "append" to add lists together
+;; Use "append" to add lists together
(append '(1 2) '(3 4)) ; => (1 2 3 4)
;;; Vectors
-; Vectors are fixed-length arrays
+;; Vectors are fixed-length arrays
#(1 2 3) ; => '#(1 2 3)
-; Use "vector-append" to add vectors together
+;; Use "vector-append" to add vectors together
(vector-append #(1 2 3) #(4 5 6)) ; => #(1 2 3 4 5 6)
;;; Sets
-; create a set from a list
+;; create a set from a list
(list->set '(1 2 3 1 2 3 3 2 1 3 2 1)) ; => (set 1 2 3)
-; Add a member with "set-add"
+;; Add a member with "set-add"
(set-add (set 1 2 3) 4); => (set 1 2 3 4)
-; Remove one with "set-remove"
+;; Remove one with "set-remove"
(set-remove (set 1 2 3) 1) ; => (set 2 3)
-; Test for existence with "set-member?"
+;; Test for existence with "set-member?"
(set-member? (set 1 2 3) 1) ; => #t
(set-member? (set 1 2 3) 4) ; => #f
;;; Hashes
-; Create an immutable hash table (There are also mutables ones)
+;; Create an immutable hash table (There are also mutables ones)
(define m (hash 'a 1 'b 2 'c 3))
-; Retrieve a value
+;; Retrieve a value
(hash-ref m 'a) ; => 1
-; Retrieving a non-present value is an exception
+;; Retrieving a non-present value is an exception
; (hash-ref m 'd) => no value found
-; You can provide a default value for missing keys
+;; You can provide a default value for missing keys
(hash-ref m 'd 0) ; => 0
-; Use "hash-set" to extend a hash table
+;; Use "hash-set" to extend a hash table
(define m2 (hash-set m 'd 4))
m2 ; => '#hash((b . 2) (a . 1) (d . 4) (c . 3))
-; Remember, these hashes are immutable!
+;; Remember, these hashes are immutable!
m ; => '#hash((b . 2) (a . 1) (c . 3))
-; Use "hash-remove" to remove keys
+;; Use "hash-remove" to remove keys
(hash-remove m 'a) ; => '#hash((b . 2) (c . 3))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; 3. Functions
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-; Use lambda to create new functions.
-; A function always returns its last statement.
+;; Use lambda to create new functions.
+;; A function always returns its last statement.
(lambda () "Hello World") ; => #<procedure>
-; (You need extra parens to call it)
+;; (You need extra parens to call it)
((lambda () "Hello World")) ; => "Hello World"
-; Assign a function to a var
+;; Assign a function to a var
(define hello-world (lambda () "Hello World"))
(hello-world) ; => "Hello World"
-; You can shorten this to:
+;; You can shorten this to:
(define (hello-world2) "Hello World")
-; The () is the list of arguments for the function.
+;; The () is the list of arguments for the function.
(define hello
(lambda (name)
(string-append "Hello " name)))
(hello "Steve") ; => "Hello Steve"
-; You can have multi-variadic functions, too
+;; You can have multi-variadic functions, too
(define hello2
(case-lambda
[() "Hello World"]
@@ -214,12 +214,12 @@ m ; => '#hash((b . 2) (a . 1) (c . 3))
(hello2 "Jake") ; => "Hello Jake"
(hello2) ; => "Hello World"
-; Functions can pack extra arguments up in a list
+;; Functions can pack extra arguments up in a list
(define (count-args . args)
(format "You passed ~a args: ~a" (length args) args))
(count-args 1 2 3) ; => "You passed 3 args: (1 2 3)"
-; You can mix regular and packed arguments
+;; You can mix regular and packed arguments
(define (hello-count name . args)
(format "Hello ~a, you passed ~a extra args" name (length args)))
(hello-count "Finn" 1 2 3)
@@ -229,16 +229,16 @@ m ; => '#hash((b . 2) (a . 1) (c . 3))
;; 4. Equality
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-; for numbers use "="
+;; for numbers use "="
(= 3 3.0) ; => #t
(= 2 1) ; => #f
-; for object identity use "eq?"
+;; for object identity use "eq?"
(eq? 3 3) ; => #t
(eq? 3 3.0) ; => #f
(eq? (list 3) (list 3)) ; => #f
-; for collections use "equal?"
+;; for collections use "equal?"
(equal? (list 'a 'b) (list 'a 'b)) ; => #t
(equal? (list 'a 'b) (list 'b 'a)) ; => #f
@@ -253,13 +253,13 @@ m ; => '#hash((b . 2) (a . 1) (c . 3))
"this is false" ; else expression
) ; => "this is true"
-; In conditionals, all non-#f values are treated as true
+;; In conditionals, all non-#f values are treated as true
(member "Groucho" '("Harpo" "Groucho" "Zeppo")) ; => '("Groucho" "Zeppo")
(if (member "Groucho" '("Harpo" "Groucho" "Zeppo"))
'yep
'nope) ; => 'yep
-; "cond" chains a series of tests to select a result
+;; "cond" chains a series of tests to select a result
(cond
[(> 2 2) (error "wrong!")]
[(< 2 2) (error "wrong again!")]
@@ -279,7 +279,7 @@ m ; => '#hash((b . 2) (a . 1) (c . 3))
;;; Loops
-; looping can be done through recursion
+;; looping can be done through recursion
(define (loop i)
(when (< i 10)
(printf "i:~a~n" i)
@@ -287,7 +287,7 @@ m ; => '#hash((b . 2) (a . 1) (c . 3))
(loop 5) ; => i:5 i:6 ...
-; similarly, with a named let
+;; similarly, with a named let
(let loop ((i 0))
(when (< i 10)
(printf "i:~a~n" i)
@@ -304,14 +304,14 @@ m ; => '#hash((b . 2) (a . 1) (c . 3))
(for/hash ([i '(1 2 3)])
(values i (number->string i))) ; => '#hash((1 . "1") (2 . "2") (3 . "3"))
-; To combine iteration results, use "for/fold"
+;; To combine iteration results, use "for/fold"
(for/fold ([sum 0]) ([i '(1 2 3 4)])
(+ sum i)) ; => 10
;;; Sequences
-; "for" allows iteration over sequences:
-; lists, vectors, strings, sets, hash tables, etc...
+;; "for" allows iteration over sequences:
+;; lists, vectors, strings, sets, hash tables, etc...
(for ([i (in-list '(l i s t))])
(displayln i))
@@ -329,8 +329,8 @@ m ; => '#hash((b . 2) (a . 1) (c . 3))
;;; Exceptions
-; To catch an exception, use the "with-handlers" form
-; To throw an exception use "raise"
+;; To catch an exception, use the "with-handlers" form
+;; To throw an exception use "raise"
(with-handlers
([(lambda (v) (equal? v "infinity"))
(lambda (exn) +inf.0)])
@@ -340,17 +340,17 @@ m ; => '#hash((b . 2) (a . 1) (c . 3))
;; 6. Mutation
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-; Use set! to assign a new value to an existing variable
+;; Use set! to assign a new value to an existing variable
(define n 5)
(set! n 6)
n ; => 6
-; Many Racket datatypes can be immutable or mutable
-; (Pairs, Lists, Strings, Vectors, Hash Tables, etc...)
+;; Many Racket datatypes can be immutable or mutable
+;; (Pairs, Lists, Strings, Vectors, Hash Tables, etc...)
-; Use "vector" to create a mutable vector
+;; Use "vector" to create a mutable vector
(define vec (vector 2 2 3 4))
-; Use vector-set! to update a slot
+;; Use vector-set! to update a slot
(vector-set! vec 0 1)
vec ; => #(1 2 3 4)
@@ -358,7 +358,7 @@ 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
(module cake racket/base ; define a new module 'cake' based on racket/base
@@ -374,16 +374,16 @@ vec ; => #(1 2 3 4)
(printf fmt (make-string n ch))
(newline)))
-; Use "require" to import all functions from the module
+;; Use "require" to import all functions from the module
(require 'cake)
(print-cake 3)
-;(show "~a" 1 #\A) ; => error, "show" was not exported
+; (show "~a" 1 #\A) ; => error, "show" was not exported
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; 8. Classes and Objects
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-; Create a class fish%
+;; Create a class fish%
(define fish%
(class object%
(init size) ; initialization argument
@@ -395,11 +395,11 @@ vec ; => #(1 2 3 4)
(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%
+;; Create an instance of fish%
(define charlie
(new fish% [size 10]))
-; Use "send" to call an object's methods
+;; Use "send" to call an object's methods
(send charlie grow 6)
(send charlie get-size) ; => 16
@@ -407,9 +407,9 @@ vec ; => #(1 2 3 4)
;; 9. Macros
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-; Macros let you extend the syntax of the language
+;; Macros let you extend the syntax of the language
-; Let's add a while loop
+;; Let's add a while loop
(define-syntax-rule (while condition body ...)
(let loop ()
(when condition
@@ -421,7 +421,7 @@ vec ; => #(1 2 3 4)
(displayln i)
(set! i (add1 i))))
-; Macros are hygienic, you cannot clobber existing variables!
+;; Macros are hygienic, you cannot clobber existing variables!
(define-syntax-rule (swap x y)
(begin
(define tmp x)
@@ -438,7 +438,7 @@ vec ; => #(1 2 3 4)
;; 10. Contracts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-; Contracts impose constraints on values exported from modules
+;; Contracts impose constraints on values exported from modules
(module bank-account racket
(provide (contract-out
@@ -455,14 +455,13 @@ vec ; => #(1 2 3 4)
(balance) ; => 5
-; Any client that attempt to deposit a non-positive amount, will be blamed
-; (deposit -5) ; => deposit: contract violation
-; expected: positive?
-; given: -5
-; more details....
+;; Any client that attempt to deposit a non-positive amount, will be blamed
+;; (deposit -5) ; => deposit: contract violation
+;; expected: positive?
+;; given: -5
+;; more details....
```
## Further Reading
Still up for more? Try [Quick: An Introduction to Racket with Pictures](http://docs.racket-lang.org/quick/)
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