Tutorial by Examples: er

At its simplest, a property is a function which returns a Bool. prop_reverseDoesNotChangeLength xs = length (reverse xs) == length xs A property declares a high-level invariant of a program. The QuickCheck test runner will evaluate the function with 100 random inputs and check that the result is...

Java SE 8 An array of strings can be joined using the static method String.join(): String[] elements = { "foo", "bar", "foobar" }; String singleString = String.join(" + ", elements); System.out.println(singleString); // Prints "foo + bar + foobar&qu...

The quickCheck function tests a property on 100 random inputs. ghci> quickCheck prop_reverseDoesNotChangeLength +++ OK, passed 100 tests. If a property fails for some input, quickCheck prints out a counterexample. prop_reverseIsAlwaysEmpty xs = reverse xs == [] -- plainly not true for all ...

To do an insert on specific columns (as opposed to all of them) you must specify the columns you want to update. INSERT INTO USERS (FIRST_NAME, LAST_NAME) VALUES ('Stephen', 'Jiang'); This will only work if the columns that you did not list are nullable, identity, timestamp data type or compute...

To insert multiple rows of data in SQL Server 2008 or later: INSERT INTO USERS VALUES (2, 'Michael', 'Blythe'), (3, 'Linda', 'Mitchell'), (4, 'Jillian', 'Carson'), (5, 'Garrett', 'Vargas'); To insert multiple rows of data in earlier versions of SQL Server, use "UNION ALL" like so: ...

A single row of data can be inserted in two ways: INSERT INTO USERS(Id, FirstName, LastName) VALUES (1, 'Mike', 'Jones'); Or INSERT INTO USERS VALUES (1, 'Mike', 'Jones'); Note that the second insert statement only allows the values in exactly the same order as the table columns whereas in...

If you wish to copy the contents of a slice into an initially empty slice, following steps can be taken to accomplish it- Create the source slice: var sourceSlice []interface{} = []interface{}{"Hello",5.10,"World",true} Create the destination slice, with: Length =...

The Pipe Operator |> takes the result of an expression on the left and feeds it as the first parameter to a function on the right. expression |> function Use the Pipe Operator to chain expressions together and to visually document the flow of a series of functions. Consider the following:...

Fixed precision and scale decimal numbers. DECIMAL and NUMERIC are functionally equivalent. Syntax: DECIMAL ( precision [ , scale] ) NUMERIC ( precision [ , scale] ) Examples: SELECT CAST(123 AS DECIMAL(5,2)) --returns 123.00 SELECT CAST(12345.12 AS NUMERIC(10,5)) --returns 12345.12000

Exact-number data types that use integer data. Data typeRangeStoragebigint-2^63 (-9,223,372,036,854,775,808) to 2^63-1 (9,223,372,036,854,775,807)8 Bytesint-2^31 (-2,147,483,648) to 2^31-1 (2,147,483,647)4 Bytessmallint-2^15 (-32,768) to 2^15-1 (32,767)2 Bytestinyint0 to 2551 Byte

A 16-byte GUID / UUID. DECLARE @GUID UNIQUEIDENTIFIER = NEWID(); SELECT @GUID -- 'E28B3BD9-9174-41A9-8508-899A78A33540' DECLARE @bad_GUID_string VARCHAR(100) = 'E28B3BD9-9174-41A9-8508-899A78A33540_foobarbaz' SELECT @bad_GUID_string, -- 'E28B3BD9-9174-41A9-8508-899A78A33540_foobarbaz' ...

NSArray *myColors = [NSArray arrayWithObjects: @"Red", @"Green", @"Blue", @"Yellow", nil]; // Convert myColors to mutable NSMutableArray *myColorsMutable = [myColors mutableCopy];

quickCheckAll is a Template Haskell helper which finds all the definitions in the current file whose name begins with prop_ and tests them. {-# LANGUAGE TemplateHaskell #-} import Test.QuickCheck (quickCheckAll) import Data.List (sort) idempotent :: Eq a => (a -> a) -> a -> Bool ...

The -Regex parameter allows switch statements to perform regular expression matching against conditions. Example: switch -Regex ('Condition') { 'Con\D+ion' {'One or more non-digits'} 'Conditio*$' {'Zero or more "o"'} 'C.ndition' {'Any single char.'} '^C\w+ition$'...

The -Wildcard parameter allows switch statements to perform wildcard matching against conditions. Example: switch -Wildcard ('Condition') { 'Condition' {'Normal match'} 'Condit*' {'Zero or more wildcard chars.'} 'C[aoc]ndit[f-l]on' {'Range and set of chars...

The -Exact parameter enforces switch statements to perform exact, case-insensitive matching against string-conditions. Example: switch -Exact ('Condition') { 'condition' {'First Action'} 'Condition' {'Second Action'} 'conditioN' {'Third Action'} '^*ondition$' {'Fourth Action...

The -CaseSensitive parameter enforces switch statements to perform exact, case-sensitive matching against conditions. Example: switch -CaseSensitive ('Condition') { 'condition' {'First Action'} 'Condition' {'Second Action'} 'conditioN' {'Third Action'} } Output: Second Act...

The -file parameter allows the switch statement to receive input from a file. Each line of the file is evaluated by the switch statement. Example file input.txt: condition test Example switch statement: switch -file input.txt { 'condition' {'First Action'} 'test' {'Second Action...

Fixnum#to_s takes an optional base argument and represents the given number in that base: 2.to_s(2) # => "10" 3.to_s(2) # => "11" 3.to_s(3) # => "10" 10.to_s(16) # => "a" If no argument is provided, then it represents the number in bas...

Compile errors can be generated using the preprocessor. This is useful for a number of reasons some of which include, notifying a user if they are on an unsupported platform or an unsupported compiler. e.g. Return Error if gcc version is 3.0.0 or earlier. #if __GNUC__ < 3 #error "This cod...