From bd2a852ae827a979f2170f90d6bd7bca4ef7c084 Mon Sep 17 00:00:00 2001
From: Eran Medan <ehrann.mehdan@gmail.com>
Date: Wed, 7 Aug 2013 17:31:49 -0400
Subject: fixed some broken / missing markdown links and added a resource

---
 scala.html.markdown | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/scala.html.markdown b/scala.html.markdown
index fef09404..b1b3ecbf 100644
--- a/scala.html.markdown
+++ b/scala.html.markdown
@@ -408,9 +408,11 @@ for(line <- Source.fromPath("myfile.txt").getLines())
 
 [Scala for the impatient](http://horstmann.com/scala/)
 
-[Twitter Scala school(http://twitter.github.io/scala_school/)
+[Twitter Scala school](http://twitter.github.io/scala_school/)
 
-[The scala documentation]
+[The scala documentation](http://docs.scala-lang.org/)
+
+[Try Scala in your browser](http://scalatutorials.com/tour/)
 
 Join the [Scala user group](https://groups.google.com/forum/#!forum/scala-user)
 
-- 
cgit v1.2.3


From 10ffa5a7815ae40803ad409dd25170883291e498 Mon Sep 17 00:00:00 2001
From: michaelstewart <stewartizer@gmail.com>
Date: Thu, 8 Aug 2013 18:49:45 +1000
Subject: Added an apostrophe to Its

---
 python.html.markdown | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/python.html.markdown b/python.html.markdown
index a32db51a..f0b74d08 100644
--- a/python.html.markdown
+++ b/python.html.markdown
@@ -6,7 +6,7 @@ filename: learnpython.py
 ---
 
 Python was created by Guido Van Rossum in the early 90's. It is now one of the most popular
-languages in existence. I fell in love with Python for its syntactic clarity. Its basically
+languages in existence. I fell in love with Python for its syntactic clarity. It's basically
 executable pseudocode.
 
 Feedback would be highly appreciated! You can reach me at [@louiedinh](http://twitter.com/louiedinh) or louiedinh [at] [google's email service]
-- 
cgit v1.2.3


From 97a99b0ad55894631bcca03e086a2f23033c7c4b Mon Sep 17 00:00:00 2001
From: m5o <m5o@gmx.com>
Date: Thu, 8 Aug 2013 12:17:10 +0200
Subject: fix indentation by 2 spaces

---
 ruby.html.markdown | 60 +++++++++++++++++++++++++++---------------------------
 1 file changed, 30 insertions(+), 30 deletions(-)

diff --git a/ruby.html.markdown b/ruby.html.markdown
index 99817982..861a94ad 100644
--- a/ruby.html.markdown
+++ b/ruby.html.markdown
@@ -275,36 +275,36 @@ surround { puts 'hello world' }
 # Define a class with the class keyword
 class Human
 
-     # A class variable. It is shared by all instances of this class.
-    @@species = "H. sapiens"
-
-    # Basic initializer
-    def initialize(name, age=0)
-        # Assign the argument to the "name" instance variable for the instance
-        @name = name
-        # If no age given, we will fall back to the default in the arguments list.
-        @age = age
-    end
-
-    # Basic setter method
-    def name=(name)
-        @name = name
-    end
-
-    # Basic getter method
-    def name
-        @name
-    end
-
-    # A class method uses self to distinguish from instance methods.
-    # It can only be called on the class, not an instance.
-    def self.say(msg)
-       puts "#{msg}"
-    end
-
-    def species
-        @@species
-    end
+  # A class variable. It is shared by all instances of this class.
+  @@species = "H. sapiens"
+
+  # Basic initializer
+  def initialize(name, age=0)
+    # Assign the argument to the "name" instance variable for the instance
+    @name = name
+    # If no age given, we will fall back to the default in the arguments list.
+    @age = age
+  end
+
+  # Basic setter method
+  def name=(name)
+    @name = name
+  end
+
+  # Basic getter method
+  def name
+    @name
+  end
+
+  # A class method uses self to distinguish from instance methods.
+  # It can only be called on the class, not an instance.
+  def self.say(msg)
+    puts "#{msg}"
+  end
+
+  def species
+    @@species
+  end
 
 end
 
-- 
cgit v1.2.3


From 674e8a0eebfa15afe51c6960cec9712fa186ef45 Mon Sep 17 00:00:00 2001
From: John Cowie <john.a.cowie@gmail.com>
Date: Thu, 8 Aug 2013 17:38:06 +0100
Subject: Explain git pull default behaviour and the use of --rebase flag.

By far the pull command I use the most is 'git pull --rebase', so wanted to add some info to make it clear that that's possible.
---
 git.html.markdown | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/git.html.markdown b/git.html.markdown
index 00f38d60..d8537300 100644
--- a/git.html.markdown
+++ b/git.html.markdown
@@ -310,7 +310,12 @@ Pulls from a repository and merges it with another branch.
 # Update your local repo, by merging in new changes
 # from the remote "origin" and "master" branch.
 # git pull <remote> <branch>
+# git pull => implicitly defaults to => git pull origin master
 $ git pull origin master
+
+# Merge in changes from remote branch and rebase
+# branch commits onto your local repo, like: "git pull <remote> <branch>, git rebase <branch>"
+$ git pull origin master --rebase
 ```
 
 ### push
-- 
cgit v1.2.3


From 29bbaff5a6ed60f40cc710a6ad79434de4d95d75 Mon Sep 17 00:00:00 2001
From: i <isomorphisms@sdf.org>
Date: Thu, 8 Aug 2013 14:52:59 -0400
Subject: wording

Compiling in LaTeX isn't that easy, actually...
---
 r.html.markdown | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/r.html.markdown b/r.html.markdown
index 0240e8fb..3339a07e 100644
--- a/r.html.markdown
+++ b/r.html.markdown
@@ -5,7 +5,7 @@ contributors:
 filename: learnr.r
 ---
 
-R is a statistical computing language. It has lots of good built-in functions for uploading and cleaning data sets, running common statistical tests, and making graphs. You can also easily compile it within a LaTeX document.
+R is a statistical computing language. It has lots of libraries for uploading and cleaning data sets, running statistical procedures, and making graphs. You can also run `R`commands within a LaTeX document.
 
 ```python
 
-- 
cgit v1.2.3


From 946a450995d874c807faa16a5df817ca80a7ecb0 Mon Sep 17 00:00:00 2001
From: i <isomorphisms@sdf.org>
Date: Thu, 8 Aug 2013 15:05:01 -0400
Subject: '/' is a character

Do you mean no letters?
---
 haskell.html.markdown | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/haskell.html.markdown b/haskell.html.markdown
index be7d8669..9847ef2a 100644
--- a/haskell.html.markdown
+++ b/haskell.html.markdown
@@ -131,7 +131,7 @@ add 1 2 -- 3
 -- with backticks:
 1 `add` 2 -- 3
 
--- You can also define functions that have no characters! This lets
+-- You can also define functions that have no letters! This lets
 -- you define your own operators! Here's an operator that does
 -- integer division
 (//) a b = a `div` b
-- 
cgit v1.2.3


From ee1b3546ad1a1a0601f2dc413d0b96f345c27ad9 Mon Sep 17 00:00:00 2001
From: i <isomorphisms@sdf.org>
Date: Thu, 8 Aug 2013 17:50:52 -0400
Subject: Update r.html.markdown

significant changes. style changes (no !, no =>). content additions. start by showing off R's non-programming features before getting to the language per se.
---
 r.html.markdown | 311 ++++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 246 insertions(+), 65 deletions(-)

diff --git a/r.html.markdown b/r.html.markdown
index 0240e8fb..61140be5 100644
--- a/r.html.markdown
+++ b/r.html.markdown
@@ -16,61 +16,242 @@ R is a statistical computing language. It has lots of good built-in functions fo
 
 # Hit COMMAND-ENTER to execute a line
 
+
+###################################################################
+# Stuff you can do without understanding anything about programming
+###################################################################
+
+data()	# Browse pre-loaded data sets
+data(rivers)	# Lengths of Major North American Rivers
+ls()	# Notice that "rivers" appears in the workspace
+head(rivers)	# peek at the dataset
+# 735 320 325 392 524 450
+length(rivers)	# how many rivers were measured?
+# 141
+summary(rivers)
+#   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
+#  135.0   310.0   425.0   591.2   680.0  3710.0 
+stem(rivers)	#stem-and-leaf plot (like a histogram)
+#
+#  The decimal point is 2 digit(s) to the right of the |
+#
+#   0 | 4
+#   2 | 011223334555566667778888899900001111223333344455555666688888999
+#   4 | 111222333445566779001233344567
+#   6 | 000112233578012234468
+#   8 | 045790018
+#  10 | 04507
+#  12 | 1471
+#  14 | 56
+#  16 | 7
+#  18 | 9
+#  20 | 
+#  22 | 25
+#  24 | 3
+#  26 | 
+#  28 | 
+#  30 | 
+#  32 | 
+#  34 | 
+#  36 | 1
+
+
+stem(log(rivers))	#Notice that the data are neither normal nor log-normal! Take that, Bell Curve fundamentalists.
+
+#  The decimal point is 1 digit(s) to the left of the |
+#
+#  48 | 1
+#  50 | 
+#  52 | 15578
+#  54 | 44571222466689
+#  56 | 023334677000124455789
+#  58 | 00122366666999933445777
+#  60 | 122445567800133459
+#  62 | 112666799035
+#  64 | 00011334581257889
+#  66 | 003683579
+#  68 | 0019156
+#  70 | 079357
+#  72 | 89
+#  74 | 84
+#  76 | 56
+#  78 | 4
+#  80 | 
+#  82 | 2
+
+
+hist(rivers, col="#333333", border="white", breaks=25)	#play around with these parameters
+hist(log(rivers), col="#333333", border="white", breaks=25)	#you'll do more plotting later
+
+#Here's another neat data set that comes pre-loaded. R has tons of these. data()
+data(discoveries)
+plot(discoveries, col="#333333", lwd=3, xlab="Year", main="Number of important discoveries per year")
+plot(discoveries, col="#333333", lwd=3, type = "h", xlab="Year", main="Number of important discoveries per year")
+
+
+#rather than leaving the default ordering (by year) we could also sort to see what's typical
+sort(discoveries)
+#  [1]  0  0  0  0  0  0  0  0  0  1  1  1  1  1  1  1  1  1  1  1  1  2  2  2  2
+# [26]  2  2  2  2  2  2  2  2  2  2  2  2  2  2  2  2  2  2  2  2  2  2  3  3  3
+# [51]  3  3  3  3  3  3  3  3  3  3  3  3  3  3  3  3  3  4  4  4  4  4  4  4  4
+# [76]  4  4  4  4  5  5  5  5  5  5  5  6  6  6  6  6  6  7  7  7  7  8  9 10 12
+
+stem(discoveries, scale=2)
+# 
+#  The decimal point is at the |
+#
+#   0 | 000000000
+#   1 | 000000000000
+#   2 | 00000000000000000000000000
+#   3 | 00000000000000000000
+#   4 | 000000000000
+#   5 | 0000000
+#   6 | 000000
+#   7 | 0000
+#   8 | 0
+#   9 | 0
+#  10 | 0
+#  11 | 
+#  12 | 0
+
+max(discoveries)
+# 12
+
+summary(discoveries)
+#   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
+#    0.0     2.0     3.0     3.1     4.0    12.0 
+
+
+
+
+#Basic statistical operations don't require any programming knowledge either
+
+#roll a die a few times
+round(runif(7, min=.5, max=6.5))
+# 1 4 6 1 4 6 4
+
+#your numbers will differ from mine unless we set the same random.seed(31337)
+
+
+#draw from a standard Gaussian 9 times
+rnorm(9)
+# [1]  0.07528471  1.03499859  1.34809556 -0.82356087  0.61638975 -1.88757271
+# [7] -0.59975593  0.57629164  1.08455362
+
+
+
+
+
+
+
+
+
 #########################
-# The absolute basics
+# Basic programming stuff
 #########################
 
 # NUMBERS
 
-# We've got doubles! Behold the "numeric" class
-5 # => [1] 5
-class(5) # => [1] "numeric"
-# We've also got integers! They look suspiciously similar,
-# but indeed are different
-5L # => [1] 5
-class(5L) # => [1] "integer"
+# "numeric" means double-precision floating-point numbers
+5	# 5
+class(5)	# "numeric"
+5e4	# 50000				#handy when dealing with large,small,or variable orders of magnitude
+6.02e23	# Avogadro's number
+1.6e-35	# Planck length
+
+# long-storage integers are written with L
+5L	# 5
+class(5L)	# "integer"
+
 # Try ?class for more information on the class() function
-# In fact, you can look up the documentation on just about anything with ?
+# In fact, you can look up the documentation on `xyz` with ?xyz
+# or see the source for `xyz` by evaluating xyz
+
+# Arithmetic
+10 + 66	# 76
+53.2 - 4	# 49.2
+2 * 2.0	# 4
+3L / 4	# 0.75
+3 %% 2	# 1
+
+# Weird number types
+class(NaN)	# "numeric"
+class(Inf)	# "numeric"
+class(-Inf)	# "numeric"		#used in for example integrate( dnorm(x), 3, Inf ) -- which obviates Z-score tables
+
+# but beware, NaN isn't the only weird type...
+class(NA)	# see below
+class(NULL)	# NULL
+
+
+# SIMPLE LISTS
+c(6, 8, 7, 5, 3, 0, 9)	# 6 8 7 5 3 0 9
+c('alef', 'bet', 'gimmel', 'dalet', 'he')	# "alef"   "bet"    "gimmel" "dalet"  "he"
+c('Z', 'o', 'r', 'o') == "Zoro"	# FALSE FALSE FALSE FALSE
+
+#some more nice built-ins
+5:15	# 5  6  7  8  9 10 11 12 13 14 15
+
+seq(from=0, to=31337, by=1337)
+#  [1]     0  1337  2674  4011  5348  6685  8022  9359 10696 12033 13370 14707
+# [13] 16044 17381 18718 20055 21392 22729 24066 25403 26740 28077 29414 30751
+
+letters
+#  [1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s"
+# [20] "t" "u" "v" "w" "x" "y" "z"
+
+month.abb	# "Jan" "Feb" "Mar" "Apr" "May" "Jun" "Jul" "Aug" "Sep" "Oct" "Nov" "Dec"
+
+
+# Access the n'th element of a list with list.name[n] or sometimes list.name[[n]]
+letters[18]	# "r"
+LETTERS[13]	# "M"
+month.name[9]	# "September"
+c(6, 8, 7, 5, 3, 0, 9)[3]	# 7
 
-# All the normal operations!
-10 + 66 # => [1] 76
-53.2 - 4 # => [1] 49.2
-2 * 2.0 # => [1] 4
-3L / 4 # => [1] 0.75
-3 %% 2 # => [1] 1
 
-# Finally, we've got not-a-numbers! They're numerics too
-class(NaN) # => [1] "numeric"
 
 # CHARACTERS
 
-# We've (sort of) got strings! Behold the "character" class
-"plugh" # => [1] "plugh"
-class("plugh") # "character"
 # There's no difference between strings and characters in R
 
+"Horatio"	# "Horatio"
+class("Horatio") # "character"
+substr("Fortuna multis dat nimis, nulli satis.", 9, 15)	# "multis "
+gsub('u', 'ø', "Fortuna multis dat nimis, nulli satis.")	# "Fortøna møltis dat nimis, nølli satis."
+
+
+
 # LOGICALS
 
-# We've got booleans! Behold the "logical" class
-class(TRUE) # => [1] "logical"
-class(FALSE) # => [1] "logical"
+# booleans
+class(TRUE)	# "logical"
+class(FALSE)	# "logical"
 # Behavior is normal
-TRUE == TRUE # => [1] TRUE
-TRUE == FALSE # => [1] FALSE
-FALSE != FALSE # => [1] FALSE
-FALSE != TRUE # => [1] TRUE
+TRUE == TRUE	# TRUE
+TRUE == FALSE	# FALSE
+FALSE != FALSE	# FALSE
+FALSE != TRUE	# TRUE
 # Missing data (NA) is logical, too
-class(NA) # => [1] "logical"
+class(NA)	# "logical"
+
+
 
 # FACTORS
 
 # The factor class is for categorical data
-# It has an attribute called levels that describes all the possible categories
-factor("dog")
-# =>
-# [1] dog
-# Levels: dog
-# (This will make more sense once we start talking about vectors)
+# which can be ordered (like childrens' grade levels)
+# or unordered (like gender)
+levels(factor(c("female", "male", "male", "female", "NA", "female")))	# "female" "male"   "NA" 
+
+factor(c("female", "female", "male", "NA", "female"))
+#  female female male   NA     female
+# Levels: female male NA
+
+data(infert)	#Infertility after Spontaneous and Induced Abortion
+levels(infert$education)	# "0-5yrs"  "6-11yrs" "12+ yrs"
+
+
 
 # VARIABLES
 
@@ -80,8 +261,8 @@ y <- "1" # this is preferred
 TRUE -> z # this works but is weird
 
 # We can use coerce variables to different classes
-as.numeric(y) # => [1] 1
-as.character(x) # => [1] "5"
+as.numeric(y)	# 1
+as.character(x)	# "5"
 
 # LOOPS
 
@@ -122,7 +303,7 @@ myFunc <- function(x) {
 }
 
 # Called like any other R function:
-myFunc(5) # => [1] 19
+myFunc(5)	# 19
 
 #########################
 # Fun with data: vectors, matrices, data frames, and arrays
@@ -132,35 +313,35 @@ myFunc(5) # => [1] 19
 
 # You can vectorize anything, so long as all components have the same type
 vec <- c(8, 9, 10, 11)
-vec # => [1]  8  9 10 11
+vec	#  8  9 10 11
 # The class of a vector is the class of its components
-class(vec) # => [1] "numeric"
+class(vec)	# "numeric"
 # If you vectorize items of different classes, weird coercions happen
-c(TRUE, 4) # => [1] 1 4
-c("dog", TRUE, 4) # => [1] "dog"  "TRUE" "4"
+c(TRUE, 4)	# 1 4
+c("dog", TRUE, 4)	# "dog"  "TRUE" "4"
 
 # We ask for specific components like so (R starts counting from 1)
-vec[1] # => [1] 8
+vec[1]	# 8
 # We can also search for the indices of specific components,
-which(vec %% 2 == 0) # => [1] 1 3
+which(vec %% 2 == 0)	# 1 3
 # or grab just the first or last entry in the vector
-head(vec, 1) # => [1] 8
-tail(vec, 1) # => [1] 11
+head(vec, 1)	# 8
+tail(vec, 1)	# 11
 # If an index "goes over" you'll get NA:
-vec[6] # => [1] NA
+vec[6]	# NA
 # You can find the length of your vector with length()
-length(vec) # => [1] 4
+length(vec)	# 4
 
 # You can perform operations on entire vectors or subsets of vectors
-vec * 4 # => [1] 16 20 24 28
-vec[2:3] * 5 # => [1] 25 30
+vec * 4	# 16 20 24 28
+vec[2:3] * 5	# 25 30
 # and there are many built-in functions to summarize vectors
-mean(vec) # => [1] 9.5
-var(vec) # => [1] 1.666667
-sd(vec) # => [1] 1.290994
-max(vec) # => [1] 11
-min(vec) # => [1] 8
-sum(vec) # => [1] 38
+mean(vec)	# 9.5
+var(vec)	# 1.666667
+sd(vec)	# 1.290994
+max(vec)	# 11
+min(vec)	# 8
+sum(vec)	# 38
 
 # TWO-DIMENSIONAL (ALL ONE CLASS)
 
@@ -175,11 +356,11 @@ mat
 # Unlike a vector, the class of a matrix is "matrix", no matter what's in it
 class(mat) # => "matrix"
 # Ask for the first row
-mat[1,] # => [1] 1 4
+mat[1,]	# 1 4
 # Perform operation on the first column
-3 * mat[,1] # => [1] 3 6 9
+3 * mat[,1]	# 3 6 9
 # Ask for a specific cell
-mat[3,2] # => [1] 6
+mat[3,2]	# 6
 # Transpose the whole matrix
 t(mat)
 # =>
@@ -196,7 +377,7 @@ mat2
 # [2,] "2"  "cat"  
 # [3,] "3"  "bird" 
 # [4,] "4"  "dog"
-class(mat2) # => [1] matrix
+class(mat2)	# matrix
 # Again, note what happened!
 # Because matrices must contain entries all of the same class,
 # everything got converted to the character class
@@ -216,7 +397,7 @@ mat3
 # For columns of different classes, use the data frame
 dat <- data.frame(c(5,2,1,4), c("dog", "cat", "bird", "dog"))
 names(dat) <- c("number", "species") # name the columns
-class(dat) # => [1] "data.frame"
+class(dat)	# "data.frame"
 dat
 # =>
 #   number species
@@ -224,14 +405,14 @@ dat
 # 2      2     cat
 # 3      1    bird
 # 4      4     dog
-class(dat$number) # => [1] "numeric"
-class(dat[,2]) # => [1] "factor"
+class(dat$number)	# "numeric"
+class(dat[,2])	# "factor"
 # The data.frame() function converts character vectors to factor vectors
 
 # There are many twisty ways to subset data frames, all subtly unalike
-dat$number # => [1] 5 2 1 4
-dat[,1] # => [1] 5 2 1 4
-dat[,"number"] # => [1] 5 2 1 4
+dat$number	# 5 2 1 4
+dat[,1]	# 5 2 1 4
+dat[,"number"]	# 5 2 1 4
 
 # MULTI-DIMENSIONAL (ALL OF ONE CLASS)
 
-- 
cgit v1.2.3


From fbfca446ff92ab9dec38569cecf250b82ab4aabc Mon Sep 17 00:00:00 2001
From: i <isomorphisms@sdf.org>
Date: Thu, 8 Aug 2013 17:51:32 -0400
Subject: Update r.html.markdown

...only in Windows
---
 r.html.markdown | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/r.html.markdown b/r.html.markdown
index 61140be5..5f143150 100644
--- a/r.html.markdown
+++ b/r.html.markdown
@@ -14,7 +14,7 @@ R is a statistical computing language. It has lots of good built-in functions fo
 # You can't make a multi-line comment per se,
 # but you can stack multiple comments like so.
 
-# Hit COMMAND-ENTER to execute a line
+# in Windows, hit COMMAND-ENTER to execute a line
 
 
 ###################################################################
-- 
cgit v1.2.3


From c4caaf42aab215e642f1212befb18f288511b542 Mon Sep 17 00:00:00 2001
From: Eran Medan <ehrann.mehdan@gmail.com>
Date: Fri, 9 Aug 2013 14:58:39 -0400
Subject: Updated most requested languages :)

---
 README.markdown | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/README.markdown b/README.markdown
index 77e09abd..efc2fa07 100644
--- a/README.markdown
+++ b/README.markdown
@@ -16,8 +16,9 @@ properly!
 
 The most requested languages are:
 
-* Scala
-* Javascript
+* Go
+* ~~Scala~~
+* ~~Javascript~~
 
 ... but there are many more requests to do "every language", so don't let that stop you.
 
-- 
cgit v1.2.3


From 8d0a2e6b79533856e82a8541b5b866ebd6fdeb4e Mon Sep 17 00:00:00 2001
From: hanguokai <han.guokai@gmail.com>
Date: Sat, 10 Aug 2013 06:31:51 +0800
Subject: add translation for dart.

---
 zh-cn/dart-cn.html.markdown | 509 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 509 insertions(+)
 create mode 100644 zh-cn/dart-cn.html.markdown

diff --git a/zh-cn/dart-cn.html.markdown b/zh-cn/dart-cn.html.markdown
new file mode 100644
index 00000000..47b1a93b
--- /dev/null
+++ b/zh-cn/dart-cn.html.markdown
@@ -0,0 +1,509 @@
+---
+language: dart
+filename: learndart.dart
+contributors:
+    - ["Joao Pedrosa", "https://github.com/jpedrosa/"]
+translators:
+    - ["Guokai Han", "https://github.com/hanguokai/"]
+---
+
+Dart 是编程语言王国的新人。
+它借鉴了许多其他主流语言，并且不会偏离它的兄弟语言 JavaScript 太多。
+就像 JavaScript，Dart 的目标是提供良好的浏览器集成。
+
+Dart 最有争议的特性必然是它的可选类型。
+
+```javascript
+import "dart:collection";
+import "dart:math" as DM;
+
+// Welcome to Learn Dart in 15 minutes. http://www.dartlang.org/
+// This is an executable tutorial. You can run it with Dart or on
+// the Try Dart! site if you copy/paste it there. http://try.dartlang.org/
+
+// Function declaration and method declaration look the same. Function
+// declarations can be nested. The declaration takes the form of
+// name() {} or name() => singleLineExpression;
+// The fat arrow function declaration has an implicit return for the result of
+// the expression.
+example1() {
+  example1nested1() {
+    example1nested2() => print("Example1 nested 1 nested 2");
+    example1nested2();
+  }
+  example1nested1();
+}
+
+// Anonymous functions don't include a name.
+example2() {
+  example2nested1(fn) {
+    fn();
+  }
+  example2nested1(() => print("Example2 nested 1"));
+}
+
+// When a function parameter is declared, the declaration can include the
+// number of parameters the function takes by specifying the names of the
+// parameters it takes.
+example3() {
+  example3nested1(fn(informSomething)) {
+    fn("Example3 nested 1");
+  }
+  example3planB(fn) { // Or don't declare number of parameters.
+    fn("Example3 plan B");
+  }
+  example3nested1((s) => print(s));
+  example3planB((s) => print(s));
+}
+
+// Functions have closure access to outer variables.
+var example4Something = "Example4 nested 1";
+example4() {
+  example4nested1(fn(informSomething)) {
+    fn(example4Something);
+  }
+  example4nested1((s) => print(s));
+}
+
+// Class declaration with a sayIt method, which also has closure access
+// to the outer variable as though it were a function as seen before.
+var example5method = "Example5 sayIt";
+class Example5Class {
+  sayIt() {
+    print(example5method);
+  }
+}
+example5() {
+  // Create an anonymous instance of the Example5Class and call the sayIt
+  // method on it.
+  new Example5Class().sayIt();
+}
+
+// Class declaration takes the form of class name { [classBody] }.
+// Where classBody can include instance methods and variables, but also
+// class methods and variables.
+class Example6Class {
+  var example6InstanceVariable = "Example6 instance variable"; 
+  sayIt() {
+    print(example6InstanceVariable);
+  }
+}
+example6() {
+  new Example6Class().sayIt();
+}
+
+// Class methods and variables are declared with "static" terms.
+class Example7Class {
+  static var example7ClassVariable = "Example7 class variable"; 
+  static sayItFromClass() {
+    print(example7ClassVariable);
+  }
+  sayItFromInstance() {
+    print(example7ClassVariable);
+  }
+}
+example7() {
+  Example7Class.sayItFromClass();
+  new Example7Class().sayItFromInstance();
+}
+
+// Literals are great, but there's a restriction for what literals can be
+// outside of function/method bodies. Literals on the outer scope of class
+// or outside of class have to be constant. Strings and numbers are constant
+// by default. But arrays and maps are not. They can be made constant by
+// declaring them "const".
+var example8A = const ["Example8 const array"],
+  example8M = const {"someKey": "Example8 const map"}; 
+example8() {
+  print(example8A[0]);
+  print(example8M["someKey"]);
+}
+
+// Loops in Dart take the form of standard for () {} or while () {} loops,
+// slightly more modern for (.. in ..) {}, or functional callbacks with many
+// supported features, starting with forEach.
+var example9A = const ["a", "b"];
+example9() {
+  for (var i = 0; i < example9A.length; i++) {
+    print("Example9 for loop '${example9A[i]}'");
+  }
+  var i = 0;
+  while (i < example9A.length) {
+    print("Example9 while loop '${example9A[i]}'");
+    i++;
+  }
+  for (var e in example9A) {
+    print("Example9 for-in loop '${e}'");
+  }
+  example9A.forEach((e) => print("Example9 forEach loop '${e}'"));
+}
+
+// To loop over the characters of a string or to extract a substring.
+var example10S = "ab";
+example10() {
+  for (var i = 0; i < example10S.length; i++) {
+    print("Example10 String character loop '${example10S[i]}'");
+  }
+  for (var i = 0; i < example10S.length; i++) {
+    print("Example10 substring loop '${example10S.substring(i, i + 1)}'");
+  }
+}
+
+// Int and double are the two supported number formats.
+example11() {
+  var i = 1 + 320, d = 3.2 + 0.01;
+  print("Example11 int ${i}");
+  print("Example11 double ${d}");
+}
+
+// DateTime provides date/time arithmetic.
+example12() {
+  var now = new DateTime.now();
+  print("Example12 now '${now}'");
+  now = now.add(new Duration(days: 1));
+  print("Example12 tomorrow '${now}'");
+}
+
+// Regular expressions are supported.
+example13() {
+  var s1 = "some string", s2 = "some", re = new RegExp("^s.+?g\$");
+  match(s) {
+    if (re.hasMatch(s)) {
+      print("Example13 regexp matches '${s}'");
+    } else {
+      print("Example13 regexp doesn't match '${s}'");
+    }
+  }
+  match(s1);
+  match(s2);
+}
+
+// Boolean expressions need to resolve to either true or false, as no
+// implicit conversions are supported.
+example14() {
+  var v = true;
+  if (v) {
+    print("Example14 value is true");
+  }
+  v = null;
+  try {
+    if (v) {
+      // Never runs
+    } else {
+      // Never runs
+    }
+  } catch (e) {
+    print("Example14 null value causes an exception: '${e}'");
+  }
+}
+
+// try/catch/finally and throw are used for exception handling.
+// throw takes any object as parameter;
+example15() {
+  try {
+    try {
+      throw "Some unexpected error.";
+    } catch (e) {
+      print("Example15 an exception: '${e}'");
+      throw e; // Re-throw
+    }
+  } catch (e) {
+    print("Example15 catch exception being re-thrown: '${e}'");
+  } finally {
+    print("Example15 Still run finally");
+  }
+}
+
+// To be efficient when creating a long string dynamically, use
+// StringBuffer. Or you could join a string array.
+example16() {
+  var sb = new StringBuffer(), a = ["a", "b", "c", "d"], e;
+  for (e in a) { sb.write(e); }
+  print("Example16 dynamic string created with "
+    "StringBuffer '${sb.toString()}'");
+  print("Example16 join string array '${a.join()}'");
+}
+
+// Strings can be concatenated by just having string literals next to
+// one another with no further operator needed.
+example17() {
+  print("Example17 "
+      "concatenate "
+      "strings "
+      "just like that");
+}
+
+// Strings have single-quote or double-quote for delimiters with no
+// actual difference between the two. The given flexibility can be good
+// to avoid the need to escape content that matches the delimiter being
+// used. For example, double-quotes of HTML attributes if the string
+// contains HTML content.
+example18() {
+  print('Example18 <a href="etc">'
+      "Don't can't I'm Etc"
+      '</a>');
+}
+
+// Strings with triple single-quotes or triple double-quotes span
+// multiple lines and include line delimiters.
+example19() {
+  print('''Example19 <a href="etc"> 
+Example19 Don't can't I'm Etc
+Example19 </a>''');
+}
+
+// Strings have the nice interpolation feature with the $ character.
+// With $ { [expression] }, the return of the expression is interpolated.
+// $ followed by a variable name interpolates the content of that variable.
+// $ can be escaped like so \$ to just add it to the string instead.
+example20() {
+  var s1 = "'\${s}'", s2 = "'\$s'";
+  print("Example20 \$ interpolation ${s1} or $s2 works.");
+}
+
+// Optional types allow for the annotation of APIs and come to the aid of
+// IDEs so the IDEs can better refactor, auto-complete and check for
+// errors. So far we haven't declared any types and the programs have
+// worked just fine. In fact, types are disregarded during runtime.
+// Types can even be wrong and the program will still be given the
+// benefit of the doubt and be run as though the types didn't matter.
+// There's a runtime parameter that checks for type errors which is
+// the checked mode, which is said to be useful during development time,
+// but which is also slower because of the extra checking and is thus
+// avoided during deployment runtime.
+class Example21 {
+  List<String> _names;
+  Example21() {
+    _names = ["a", "b"]; 
+  }
+  List<String> get names => _names;
+  set names(List<String> list) {
+    _names = list;
+  }
+  int get length => _names.length;
+  void add(String name) {
+    _names.add(name);
+  }
+}
+void example21() {
+  Example21 o = new Example21();
+  o.add("c");
+  print("Example21 names '${o.names}' and length '${o.length}'");
+  o.names = ["d", "e"];
+  print("Example21 names '${o.names}' and length '${o.length}'");
+}
+
+// Class inheritance takes the form of class name extends AnotherClassName {}.
+class Example22A {
+  var _name = "Some Name!";
+  get name => _name;
+}
+class Example22B extends Example22A {}
+example22() {
+  var o = new Example22B();
+  print("Example22 class inheritance '${o.name}'");
+}
+
+// Class mixin is also available, and takes the form of
+// class name extends SomeClass with AnotherClassName {}.
+// It's necessary to extend some class to be able to mixin another one.
+// The template class of mixin cannot at the moment have a constructor.
+// Mixin is mostly used to share methods with distant classes, so the
+// single inheritance doesn't get in the way of reusable code.
+// Mixins follow the "with" statement during the class declaration.
+class Example23A {}
+class Example23Utils {
+  addTwo(n1, n2) {
+    return n1 + n2;
+  }
+}
+class Example23B extends Example23A with Example23Utils {
+  addThree(n1, n2, n3) {
+    return addTwo(n1, n2) + n3;
+  }
+}
+example23() {
+  var o = new Example23B(), r1 = o.addThree(1, 2, 3),
+    r2 = o.addTwo(1, 2);
+  print("Example23 addThree(1, 2, 3) results in '${r1}'");
+  print("Example23 addTwo(1, 2) results in '${r2}'");
+}
+
+// The Class constructor method uses the same name of the class and
+// takes the form of SomeClass() : super() {}, where the ": super()"
+// part is optional and it's used to delegate constant parameters to the
+// super-parent's constructor.
+class Example24A {
+  var _value;
+  Example24A({value: "someValue"}) {
+    _value = value;
+  }
+  get value => _value;
+}
+class Example24B extends Example24A {
+  Example24B({value: "someOtherValue"}) : super(value: value);
+}
+example24() {
+  var o1 = new Example24B(),
+    o2 = new Example24B(value: "evenMore");
+  print("Example24 calling super during constructor '${o1.value}'");
+  print("Example24 calling super during constructor '${o2.value}'");
+}
+
+// There's a shortcut to set constructor parameters in case of simpler classes.
+// Just use the this.parameterName prefix and it will set the parameter on
+// an instance variable of same name.
+class Example25 {
+  var value, anotherValue;
+  Example25({this.value, this.anotherValue});
+}
+example25() {
+  var o = new Example25(value: "a", anotherValue: "b");
+  print("Example25 shortcut for constructor '${o.value}' and "
+    "'${o.anotherValue}'");
+}
+
+// Named parameters are available when declared between {}.
+// Parameter order can be optional when declared between {}.
+// Parameters can be made optional when declared between [].
+example26() {
+  var _name, _surname, _email;
+  setConfig1({name, surname}) {
+    _name = name;
+    _surname = surname;
+  }
+  setConfig2(name, [surname, email]) {
+    _name = name;
+    _surname = surname;
+    _email = email;
+  }
+  setConfig1(surname: "Doe", name: "John");
+  print("Example26 name '${_name}', surname '${_surname}', "
+    "email '${_email}'");
+  setConfig2("Mary", "Jane");
+  print("Example26 name '${_name}', surname '${_surname}', "
+  "email '${_email}'");
+}
+
+// Variables declared with final can only be set once.
+// In case of classes, final instance variables can be set via constant
+// constructor parameter.
+class Example27 {
+  final color1, color2;
+  // A little flexibility to set final instance variables with syntax
+  // that follows the :
+  Example27({this.color1, color2}) : color2 = color2;
+}
+example27() {
+  final color = "orange", o = new Example27(color1: "lilac", color2: "white");
+  print("Example27 color is '${color}'");
+  print("Example27 color is '${o.color1}' and '${o.color2}'");
+}
+
+// To import a library, use import "libraryPath" or if it's a core library,
+// import "dart:libraryName". There's also the "pub" package management with
+// its own convention of import "package:packageName".
+// See import "dart:collection"; at the top. Imports must come before
+// other code declarations. IterableBase comes from dart:collection.
+class Example28 extends IterableBase {
+  var names;
+  Example28() {
+    names = ["a", "b"];
+  }
+  get iterator => names.iterator;
+}
+example28() {
+  var o = new Example28();
+  o.forEach((name) => print("Example28 '${name}'"));
+}
+
+// For control flow we have:
+// * standard switch with must break statements
+// * if-else if-else and ternary ..?..:.. operator
+// * closures and anonymous functions
+// * break, continue and return statements
+example29() {
+  var v = true ? 30 : 60;
+  switch (v) {
+    case 30:
+      print("Example29 switch statement");
+      break;
+  }
+  if (v < 30) {
+  } else if (v > 30) {
+  } else {
+    print("Example29 if-else statement");
+  }
+  callItForMe(fn()) {
+    return fn();
+  }
+  rand() {
+    v = new DM.Random().nextInt(50);
+    return v;
+  }
+  while (true) {
+    print("Example29 callItForMe(rand) '${callItForMe(rand)}'");
+    if (v != 30) {
+      break;
+    } else {
+      continue;
+    }
+    // Never gets here.
+  }
+}
+
+// Parse int, convert double to int, or just keep int when dividing numbers
+// by using the ~/ operation. Let's play a guess game too.
+example30() {
+  var gn, tooHigh = false,
+    n, n2 = (2.0).toInt(), top = int.parse("123") ~/ n2, bottom = 0;
+  top = top ~/ 6;
+  gn = new DM.Random().nextInt(top + 1); // +1 because nextInt top is exclusive
+  print("Example30 Guess a number between 0 and ${top}");
+  guessNumber(i) {
+    if (n == gn) {
+      print("Example30 Guessed right! The number is ${gn}");
+    } else {
+      tooHigh = n > gn;
+      print("Example30 Number ${n} is too "
+        "${tooHigh ? 'high' : 'low'}. Try again");
+    }
+    return n == gn;
+  }
+  n = (top - bottom) ~/ 2;
+  while (!guessNumber(n)) {
+    if (tooHigh) {
+      top = n - 1;
+    } else {
+      bottom = n + 1;
+    }
+    n = bottom + ((top - bottom) ~/ 2);
+  }
+}
+
+// Programs have only one entry point in the main function.
+// Nothing is expected to be executed on the outer scope before a program
+// starts running with what's in its main function.
+// This helps with faster loading and even lazily loading of just what
+// the program needs to startup with.
+main() {
+  print("Learn Dart in 15 minutes!");
+  [example1, example2, example3, example4, example5, example6, example7,
+    example8, example9, example10, example11, example12, example13, example14,
+    example15, example16, example17, example18, example19, example20,
+    example21, example22, example23, example24, example25, example26,
+    example27, example28, example29, example30
+    ].forEach((ef) => ef());
+}
+
+```
+
+## 延伸阅读
+
+Dart 有一个全面的网站。它涵盖了 API 参考、入门向导、文章以及更多，
+包括一个有用的 Dart 在线试用。
+http://www.dartlang.org/
+http://try.dartlang.org/
+
+
+
-- 
cgit v1.2.3


From c5c76b4a5d36b729bd782d3e3695aa1a7083a129 Mon Sep 17 00:00:00 2001
From: hanguokai <han.guokai@gmail.com>
Date: Sat, 10 Aug 2013 06:35:01 +0800
Subject: add translation for dart.

---
 zh-cn/dart-cn.html.markdown | 205 +++++++++++++++++++++-----------------------
 1 file changed, 97 insertions(+), 108 deletions(-)

diff --git a/zh-cn/dart-cn.html.markdown b/zh-cn/dart-cn.html.markdown
index 47b1a93b..64663b21 100644
--- a/zh-cn/dart-cn.html.markdown
+++ b/zh-cn/dart-cn.html.markdown
@@ -9,7 +9,7 @@ translators:
 
 Dart 是编程语言王国的新人。
 它借鉴了许多其他主流语言，并且不会偏离它的兄弟语言 JavaScript 太多。
-就像 JavaScript，Dart 的目标是提供良好的浏览器集成。
+就像 JavaScript 一样，Dart 的目标是提供良好的浏览器集成。
 
 Dart 最有争议的特性必然是它的可选类型。
 
@@ -17,15 +17,14 @@ Dart 最有争议的特性必然是它的可选类型。
 import "dart:collection";
 import "dart:math" as DM;
 
-// Welcome to Learn Dart in 15 minutes. http://www.dartlang.org/
-// This is an executable tutorial. You can run it with Dart or on
-// the Try Dart! site if you copy/paste it there. http://try.dartlang.org/
+// 欢迎进入15分钟的 Dart 学习。 http://www.dartlang.org/
+// 这是一个可实际执行的向导。你可以用 Dart 运行它
+// 或者在线执行! 可以把代码复制/粘贴到这个网站。 http://try.dartlang.org/
 
-// Function declaration and method declaration look the same. Function
-// declarations can be nested. The declaration takes the form of
-// name() {} or name() => singleLineExpression;
-// The fat arrow function declaration has an implicit return for the result of
-// the expression.
+// 函数声明和方法声明看起来一样。
+// 函数声明可以嵌套。声明使用这种 name() {} 的形式，
+// 或者 name() => 单行表达式; 的形式。
+// 右箭头的声明形式会隐式地返回表达式的结果。
 example1() {
   example1nested1() {
     example1nested2() => print("Example1 nested 1 nested 2");
@@ -34,7 +33,7 @@ example1() {
   example1nested1();
 }
 
-// Anonymous functions don't include a name.
+// 匿名函数没有函数名。
 example2() {
   example2nested1(fn) {
     fn();
@@ -42,21 +41,20 @@ example2() {
   example2nested1(() => print("Example2 nested 1"));
 }
 
-// When a function parameter is declared, the declaration can include the
-// number of parameters the function takes by specifying the names of the
-// parameters it takes.
+// 当声明函数类型的参数的时候，声明中可以包含
+// 函数参数需要的参数，指定所需的参数名即可。
 example3() {
   example3nested1(fn(informSomething)) {
     fn("Example3 nested 1");
   }
-  example3planB(fn) { // Or don't declare number of parameters.
+  example3planB(fn) { // 或者不声明函数参数的参数
     fn("Example3 plan B");
   }
   example3nested1((s) => print(s));
   example3planB((s) => print(s));
 }
 
-// Functions have closure access to outer variables.
+// 函数有可以访问到外层变量的闭包。
 var example4Something = "Example4 nested 1";
 example4() {
   example4nested1(fn(informSomething)) {
@@ -65,8 +63,8 @@ example4() {
   example4nested1((s) => print(s));
 }
 
-// Class declaration with a sayIt method, which also has closure access
-// to the outer variable as though it were a function as seen before.
+// 下面这个包含 sayIt 方法的类声明，同样有一个可以访问外层变量的闭包，
+// 就像前面的函数一样。
 var example5method = "Example5 sayIt";
 class Example5Class {
   sayIt() {
@@ -74,14 +72,14 @@ class Example5Class {
   }
 }
 example5() {
-  // Create an anonymous instance of the Example5Class and call the sayIt
-  // method on it.
+  // 创建一个 Example5Class 类的匿名实例，
+  // 并调用它的 sayIt 方法。
   new Example5Class().sayIt();
 }
 
-// Class declaration takes the form of class name { [classBody] }.
-// Where classBody can include instance methods and variables, but also
-// class methods and variables.
+// 类的声明使用这种形式 class name { [classBody] }.
+// classBody 中可以包含实例方法和变量，
+// 还可以包含类方法和变量。
 class Example6Class {
   var example6InstanceVariable = "Example6 instance variable"; 
   sayIt() {
@@ -92,7 +90,7 @@ example6() {
   new Example6Class().sayIt();
 }
 
-// Class methods and variables are declared with "static" terms.
+// 类方法和变量使用 static 关键词声明。
 class Example7Class {
   static var example7ClassVariable = "Example7 class variable"; 
   static sayItFromClass() {
@@ -107,11 +105,10 @@ example7() {
   new Example7Class().sayItFromInstance();
 }
 
-// Literals are great, but there's a restriction for what literals can be
-// outside of function/method bodies. Literals on the outer scope of class
-// or outside of class have to be constant. Strings and numbers are constant
-// by default. But arrays and maps are not. They can be made constant by
-// declaring them "const".
+// 字面量非常方便，但是对于在函数/方法的外层的字面量有一个限制，
+// 类的外层或外面的字面量必需是常量。
+// 字符串和数字默认是常量。
+// 但是 array 和 map 不是。他们需要用 "const" 声明为常量。
 var example8A = const ["Example8 const array"],
   example8M = const {"someKey": "Example8 const map"}; 
 example8() {
@@ -119,9 +116,9 @@ example8() {
   print(example8M["someKey"]);
 }
 
-// Loops in Dart take the form of standard for () {} or while () {} loops,
-// slightly more modern for (.. in ..) {}, or functional callbacks with many
-// supported features, starting with forEach.
+// Dart 中的循环使用标准的 for () {} 或 while () {} 的形式，
+// 以及更加现代的 for (.. in ..) {} 的形式, 或者
+// 以 forEach 开头并具有许多特性支持的函数回调的形式。
 var example9A = const ["a", "b"];
 example9() {
   for (var i = 0; i < example9A.length; i++) {
@@ -138,7 +135,7 @@ example9() {
   example9A.forEach((e) => print("Example9 forEach loop '${e}'"));
 }
 
-// To loop over the characters of a string or to extract a substring.
+// 遍历字符串中的每个字符或者提取其子串。
 var example10S = "ab";
 example10() {
   for (var i = 0; i < example10S.length; i++) {
@@ -149,14 +146,14 @@ example10() {
   }
 }
 
-// Int and double are the two supported number formats.
+// 支持两种数字格式 int 和 double 。
 example11() {
   var i = 1 + 320, d = 3.2 + 0.01;
   print("Example11 int ${i}");
   print("Example11 double ${d}");
 }
 
-// DateTime provides date/time arithmetic.
+// DateTime 提供了日期/时间的算法。
 example12() {
   var now = new DateTime.now();
   print("Example12 now '${now}'");
@@ -164,7 +161,7 @@ example12() {
   print("Example12 tomorrow '${now}'");
 }
 
-// Regular expressions are supported.
+// 支持正则表达式。
 example13() {
   var s1 = "some string", s2 = "some", re = new RegExp("^s.+?g\$");
   match(s) {
@@ -178,8 +175,8 @@ example13() {
   match(s2);
 }
 
-// Boolean expressions need to resolve to either true or false, as no
-// implicit conversions are supported.
+// 布尔表达式必需被解析为 true 或 false，
+// 因为不支持隐式转换。
 example14() {
   var v = true;
   if (v) {
@@ -188,17 +185,17 @@ example14() {
   v = null;
   try {
     if (v) {
-      // Never runs
+      // 不会执行
     } else {
-      // Never runs
+      // 不会执行
     }
   } catch (e) {
     print("Example14 null value causes an exception: '${e}'");
   }
 }
 
-// try/catch/finally and throw are used for exception handling.
-// throw takes any object as parameter;
+// try/catch/finally 和 throw 语句用于异常处理。
+// throw 语句可以使用任何对象作为参数。
 example15() {
   try {
     try {
@@ -214,8 +211,8 @@ example15() {
   }
 }
 
-// To be efficient when creating a long string dynamically, use
-// StringBuffer. Or you could join a string array.
+// 要想有效地动态创建长字符串，
+// 应该使用 StringBuffer。 或者 join 一个字符串的数组。
 example16() {
   var sb = new StringBuffer(), a = ["a", "b", "c", "d"], e;
   for (e in a) { sb.write(e); }
@@ -224,8 +221,8 @@ example16() {
   print("Example16 join string array '${a.join()}'");
 }
 
-// Strings can be concatenated by just having string literals next to
-// one another with no further operator needed.
+// 字符串连接只需让相邻的字符串字面量挨着，
+// 不需要额外的操作符。
 example17() {
   print("Example17 "
       "concatenate "
@@ -233,44 +230,41 @@ example17() {
       "just like that");
 }
 
-// Strings have single-quote or double-quote for delimiters with no
-// actual difference between the two. The given flexibility can be good
-// to avoid the need to escape content that matches the delimiter being
-// used. For example, double-quotes of HTML attributes if the string
-// contains HTML content.
+// 字符串使用单引号或双引号做分隔符，二者并没有实际的差异。
+// 这种灵活性可以很好地避免内容中需要转义分隔符的情况。
+// 例如，字符串内容里的 HTML 属性使用了双引号。
 example18() {
   print('Example18 <a href="etc">'
       "Don't can't I'm Etc"
       '</a>');
 }
 
-// Strings with triple single-quotes or triple double-quotes span
-// multiple lines and include line delimiters.
+// 用三个单引号或三个双引号表示的字符串
+// 可以跨越多行，并且包含行分隔符。
 example19() {
   print('''Example19 <a href="etc"> 
 Example19 Don't can't I'm Etc
 Example19 </a>''');
 }
 
-// Strings have the nice interpolation feature with the $ character.
-// With $ { [expression] }, the return of the expression is interpolated.
-// $ followed by a variable name interpolates the content of that variable.
-// $ can be escaped like so \$ to just add it to the string instead.
+// 字符串可以使用 $ 字符插入内容。
+// 使用 $ { [expression] } 的形式，表达式的值会被插入到字符串中。
+// $ 跟着一个变量名会插入变量的值。
+// 如果要在字符串中插入 $ ，可以使用 \$ 的转义形式代替。
 example20() {
   var s1 = "'\${s}'", s2 = "'\$s'";
   print("Example20 \$ interpolation ${s1} or $s2 works.");
 }
 
-// Optional types allow for the annotation of APIs and come to the aid of
-// IDEs so the IDEs can better refactor, auto-complete and check for
-// errors. So far we haven't declared any types and the programs have
-// worked just fine. In fact, types are disregarded during runtime.
-// Types can even be wrong and the program will still be given the
-// benefit of the doubt and be run as though the types didn't matter.
-// There's a runtime parameter that checks for type errors which is
-// the checked mode, which is said to be useful during development time,
-// but which is also slower because of the extra checking and is thus
-// avoided during deployment runtime.
+// 可选类型允许作为 API 的标注，并且可以辅助 IDE，
+// 这样 IDE 可以更好地提供重构、自动完成和错误检测功能。
+// 目前为止我们还没有声明任何类型，并且程序运行地很好。
+// 事实上，类型在运行时会被忽略。
+// 类型甚至可以是错的，并且程序依然可以执行，
+// 好像和类型完全无关一样。
+// 有一个运行时参数可以让程序进入检查模式，它会在运行时检查类型错误。
+// 这在开发时很有用，但是由于增加了额外的检查会使程序变慢，
+// 因此应该避免在部署时使用。
 class Example21 {
   List<String> _names;
   Example21() {
@@ -293,7 +287,7 @@ void example21() {
   print("Example21 names '${o.names}' and length '${o.length}'");
 }
 
-// Class inheritance takes the form of class name extends AnotherClassName {}.
+// 类的继承形式是 class name extends AnotherClassName {} 。
 class Example22A {
   var _name = "Some Name!";
   get name => _name;
@@ -304,13 +298,13 @@ example22() {
   print("Example22 class inheritance '${o.name}'");
 }
 
-// Class mixin is also available, and takes the form of
+// 类也可以使用 mixin 的形式 ：
 // class name extends SomeClass with AnotherClassName {}.
-// It's necessary to extend some class to be able to mixin another one.
-// The template class of mixin cannot at the moment have a constructor.
-// Mixin is mostly used to share methods with distant classes, so the
-// single inheritance doesn't get in the way of reusable code.
-// Mixins follow the "with" statement during the class declaration.
+// 必需继承某个类才能 mixin 另一个类。
+// 当前 mixin 的模板类不能有构造函数。
+// Mixin 主要是用来和辅助的类共享方法的，
+// 这样单一继承就不会影响代码复用。
+// Mixin 声明在类定义的 "with" 关键词后面。
 class Example23A {}
 class Example23Utils {
   addTwo(n1, n2) {
@@ -329,10 +323,9 @@ example23() {
   print("Example23 addTwo(1, 2) results in '${r2}'");
 }
 
-// The Class constructor method uses the same name of the class and
-// takes the form of SomeClass() : super() {}, where the ": super()"
-// part is optional and it's used to delegate constant parameters to the
-// super-parent's constructor.
+// 类的构造函数名和类名相同，形式为
+// SomeClass() : super() {},  其中 ": super()" 的部分是可选的，
+// 它用来传递参数给父类的构造函数。
 class Example24A {
   var _value;
   Example24A({value: "someValue"}) {
@@ -350,9 +343,9 @@ example24() {
   print("Example24 calling super during constructor '${o2.value}'");
 }
 
-// There's a shortcut to set constructor parameters in case of simpler classes.
-// Just use the this.parameterName prefix and it will set the parameter on
-// an instance variable of same name.
+// 对于简单的类，有一种设置构造函数参数的快捷方式。
+// 只需要使用 this.parameterName 的前缀，
+// 它就会把参数设置为同名的实例变量。
 class Example25 {
   var value, anotherValue;
   Example25({this.value, this.anotherValue});
@@ -363,9 +356,9 @@ example25() {
     "'${o.anotherValue}'");
 }
 
-// Named parameters are available when declared between {}.
-// Parameter order can be optional when declared between {}.
-// Parameters can be made optional when declared between [].
+// 可以在大括号 {} 中声明命名参数。
+// 大括号 {} 中声明的参数的顺序是随意的。
+// 在中括号 [] 中声明的参数也是可选的。 
 example26() {
   var _name, _surname, _email;
   setConfig1({name, surname}) {
@@ -385,13 +378,11 @@ example26() {
   "email '${_email}'");
 }
 
-// Variables declared with final can only be set once.
-// In case of classes, final instance variables can be set via constant
-// constructor parameter.
+// 使用 final 声明的变量只能被设置一次。
+// 在类里面，final 实例变量可以通过常量的构造函数参数设置。
 class Example27 {
   final color1, color2;
-  // A little flexibility to set final instance variables with syntax
-  // that follows the :
+  // 更灵活一点的方法是在冒号 : 后面设置 final 实例变量。
   Example27({this.color1, color2}) : color2 = color2;
 }
 example27() {
@@ -400,11 +391,11 @@ example27() {
   print("Example27 color is '${o.color1}' and '${o.color2}'");
 }
 
-// To import a library, use import "libraryPath" or if it's a core library,
-// import "dart:libraryName". There's also the "pub" package management with
-// its own convention of import "package:packageName".
-// See import "dart:collection"; at the top. Imports must come before
-// other code declarations. IterableBase comes from dart:collection.
+// 要导入一个库，使用 import "libraryPath" 的形式，或者如果要导入的是
+// 核心库使用 import "dart:libraryName" 。还有一个称为 "pub" 的包管理工具，
+// 它使用 import "package:packageName" 的约定形式。
+// 看下这个文件顶部的 import "dart:collection"; 语句。 
+// 导入语句必需在其它代码声明之前出现。IterableBase 来自于 dart:collection 。
 class Example28 extends IterableBase {
   var names;
   Example28() {
@@ -417,11 +408,11 @@ example28() {
   o.forEach((name) => print("Example28 '${name}'"));
 }
 
-// For control flow we have:
-// * standard switch with must break statements
-// * if-else if-else and ternary ..?..:.. operator
-// * closures and anonymous functions
-// * break, continue and return statements
+// 对于控制流语句，我们有：
+// * 必需带 break 的标准 switch 语句
+// * if-else 和三元操作符 ..?..:.. 
+// * 闭包和匿名函数
+// * break, continue 和 return 语句
 example29() {
   var v = true ? 30 : 60;
   switch (v) {
@@ -448,12 +439,12 @@ example29() {
     } else {
       continue;
     }
-    // Never gets here.
+    // 不会到这里。
   }
 }
 
-// Parse int, convert double to int, or just keep int when dividing numbers
-// by using the ~/ operation. Let's play a guess game too.
+// 解析 int，把 double 转成 int，或者使用 ~/ 操作符在除法计算时仅保留整数位。
+// 让我们也来场猜数游戏吧。
 example30() {
   var gn, tooHigh = false,
     n, n2 = (2.0).toInt(), top = int.parse("123") ~/ n2, bottom = 0;
@@ -481,11 +472,9 @@ example30() {
   }
 }
 
-// Programs have only one entry point in the main function.
-// Nothing is expected to be executed on the outer scope before a program
-// starts running with what's in its main function.
-// This helps with faster loading and even lazily loading of just what
-// the program needs to startup with.
+// 程序的唯一入口点是 main 函数。
+// 在程序开始执行 main 函数之前，不期望执行任何外层代码。
+// 这样可以帮助程序更快地加载，甚至仅惰性加载程序启动时需要的部分。
 main() {
   print("Learn Dart in 15 minutes!");
   [example1, example2, example3, example4, example5, example6, example7,
@@ -500,8 +489,8 @@ main() {
 
 ## 延伸阅读
 
-Dart 有一个全面的网站。它涵盖了 API 参考、入门向导、文章以及更多，
-包括一个有用的 Dart 在线试用。
+Dart 有一个综合性网站。它涵盖了 API 参考、入门向导、文章以及更多，
+还包括一个有用的在线试用 Dart 页面。
 http://www.dartlang.org/
 http://try.dartlang.org/
 
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