diff options
Diffstat (limited to 'scala.html.markdown')
| -rw-r--r-- | scala.html.markdown | 73 |
1 files changed, 43 insertions, 30 deletions
diff --git a/scala.html.markdown b/scala.html.markdown index a55e1f0e..a0983bdb 100644 --- a/scala.html.markdown +++ b/scala.html.markdown @@ -32,23 +32,36 @@ Scala - the scalable language ## 1. Basics ################################################# +// Single line comments start with two forward slashes + +/* + Multi line comments, as you can already see from above, look like this. +*/ + // Printing, and forcing a new line on the next print println("Hello world!") +println(10) + // Printing, without forcing a new line on next print print("Hello world") -// Declaring values is done using either var or val +// Declaring values is done using either var or val. // val declarations are immutable, whereas var's are mutable. Immutability is // a good thing. val x = 10 // x is now 10 x = 20 // error: reassignment to val -var x = 10 -x = 20 // x is now 20 +var y = 10 +y = 20 // y is now 20 -// Single line comments start with two forward slashes /* -Multi line comments look like this. + Scala is a statically typed language, yet note that in the above declarations, we did not specify + a type. This is due to a language feature called type inference. In most cases, Scala compiler can + guess what the type of a variable is, so you don't have to type it every time. We can explicitly + declare the type of a variable like so: */ +val z: Int = 10 +val a: Double = 1.0 +val b: Double = 10 // Notice automatic conversion from Int to Double, result is 10.0, not 10 // Boolean values true @@ -65,9 +78,11 @@ true == false // false 2 - 1 // 1 5 * 3 // 15 6 / 2 // 3 +6 / 4 // 1 +6.0 / 4 // 1.5 -// Evaluating a command in the REPL gives you the type and value of the result +// Evaluating an expression in the REPL gives you the type and value of the result 1 + 7 @@ -79,48 +94,46 @@ true == false // false This means the result of evaluating 1 + 7 is an object of type Int with a value of 8 - 1+7 will give you the same result + Note that "res29" is a sequentially generated variable name to store the results of the + expressions you typed, your output may differ. */ - -// Strings - -"Scala strings are surrounded by double quotes" // +"Scala strings are surrounded by double quotes" 'a' // A Scala Char 'Single quote strings don't exist' // Error -"Strings have the usual Java methods defined on them".length -"They also have some extra Scala methods.".reverse -// Seealso: scala.collection.immutable.StringOps +// Strings have the usual Java methods defined on them +"hello world".length +"ABCDEF".substring(2, 6) +"ABCDEF".replace("C", "3") -println("ABCDEF".length) -println("ABCDEF".substring(2, 6)) -println("ABCDEF".replace("C", "3")) +// They also have some extra Scala methods. See also: scala.collection.immutable.StringOps +"hello world".take(5) -// String interpolation +// String interpolation: notice the prefix "s" val n = 45 -println(s"We have $n apples") // => "We have 45 apples" +s"We have $n apples" // => "We have 45 apples" // Expressions inside interpolated strings are also possible val a = Array(11, 9, 6) -println(s"My second daughter is ${a(0) - a(2)} years old.") // => "My second daughter is 5 years old." -println(s"We have double the amount of ${n / 2.0} in apples.") // => "We have double the amount of 22.5 in apples." -println(s"Power of 2: ${math.pow(2, 2)}") // => "Power of 2: 4" +s"My second daughter is ${a(0) - a(2)} years old." // => "My second daughter is 5 years old." +s"We have double the amount of ${n / 2.0} in apples." // => "We have double the amount of 22.5 in apples." +s"Power of 2: ${math.pow(2, 2)}" // => "Power of 2: 4" -// Formatting with interpolated strings (note the prefixed f) -println(f"Power of 5: ${math.pow(5, 2)}%1.0f") // "Power of 5: 25" -println(f"Square root of 122: ${math.sqrt(122)}%1.4f") // "Square root of 122" +// Formatting with interpolated strings with the prefix "f" +f"Power of 5: ${math.pow(5, 2)}%1.0f" // "Power of 5: 25" +f"Square root of 122: ${math.sqrt(122)}%1.4f" // "Square root of 122" -// Ignoring special characters. -println(raw"New line feed: \n. Carriage return: \r.") // => "New line feed: \n. Carriage return: \r." +// Raw strings, ignoring special characters. +raw"New line feed: \n. Carriage return: \r." // => "New line feed: \n. Carriage return: \r." -// Some characters need to be 'escaped', e.g. a double quote inside a string: -val a = "They stood outside the \"Rose and Crown\"" // => "They stood outside the "Rose and Crown"" +// Some characters need to be "escaped", e.g. a double quote inside a string: +"They stood outside the \"Rose and Crown\"" // => "They stood outside the "Rose and Crown"" // Triple double-quotes let strings span multiple rows and contain quotes val html = """<form id="daform"> <p>Press belo', Joe</p> - | <input type="submit"> + <input type="submit"> </form>""" |