Tutorial by Examples: o

Recursion

Prolog doesn't have iteration, but all iteration can be rewritten using recursion. Recursion appears when a predicate contains a goal that refers to itself. When writing such predicates in Prolog, a standard recursive pattern always has at least two parts: Base (non-recursive) clause: Typically...

Prolog Language • Reasoning about data

Optional parameters and named arguments

We can omit the argument in the call if that argument is an Optional Argument Every Optional Argument has its own default value It will take default value if we do not supply the value A default value of a Optional Argument must be a Constant expression. Must be a value type such as enum or s...

C# Language • C# 4.0 Features

Optional ref keyword when using COM

The ref keyword for callers of methods is now optional when calling into methods supplied by COM interfaces. Given a COM method with the signature void Increment(ref int x); the invocation can now be written as either Increment(0); // no need for "ref" or a place holder variable any m...

C# Language • C# 4.0 Features

Dynamic member lookup

A new pseudo-type dynamic is introduced into the C# type system. It is treated as System.Object, but in addition, any member access (method call, field, property, or indexer access, or a delegate invocation) or application of an operator on a value of such type is permitted without any type checking...

C# Language • C# 4.0 Features

Translating a LINQ query to a SQL query

The IQueryable and IQueryable<T> interfaces allows developers to translate a LINQ query (a 'language-integrated' query) to a specific datasource, for example a relational database. Take this LINQ query written in C#: var query = from book in books where book.Author == "Steph...

C# Language • IQueryable interface

Search for nodes with name as Light, Device or Sensor

XML <Galaxy> <Light>sun</Light> <Device>satellite</Device> <Sensor>human</Sensor> <Name>Milky Way</Name> </Galaxy> XPATH /Galaxy/*[local-name()='Light' or local-name()='Device' or local-name()='Sensor'] or //*[...

xpath • Select nodes with names equal to or containing some string

Search for nodes that has name that contains Light

XML <Data> <BioLight> <name>Firefly</name> <model>Insect</model> </BioLight> <ArtificialLight> <name>Fire</name> <model>Natural element</model> <source>flint<...

xpath • Select nodes with names equal to or containing some string

Search for nodes that has name that starts with Star

XML <College> <FootBall> <Members>20</Members> <Coach>Archie Theron</Coach> <Name>Wild cats</Name> <StarFootballer>David Perry</StarFootballer> </FootBall> <Academics> ...

xpath • Select nodes with names equal to or containing some string

Search for nodes that has name that ends with Ball

XML <College> <FootBall> <Members>20</Members> <Coach>Archie Theron</Coach> <Name>Wild cats</Name> <StarPlayer>David Perry</StarPlayer> </FootBall> <VolleyBall> <Me...

xpath • Select nodes with names equal to or containing some string

Search for nodes with name light (case insensitive)

XML <Galaxy> <Light>sun</Light> <Device>satellite</Device> <Sensor>human</Sensor> <Name>Milky Way</Name> </Galaxy> XPATH /Galaxy/*[lower-case(local-name())="light"] or //*[lower-case(local-name())=&qu...

xpath • Select nodes with names equal to or containing some string

Functions with an Unknown Number of Arguments (variadic functions)

To create a function which accepts an undetermined number of arguments, there are two methods depending on your environment. 5 Whenever a function is called, it has an Array-like arguments object in its scope, containing all the arguments passed to the function. Indexing into or iterating over th...

JavaScript • Functions

Find nodes with a specific attribute

XML <Galaxy> <name>Milky Way</name> <CelestialObject name="Earth" type="planet"/> <CelestialObject name="Sun" type="star"/> </Galaxy> XPATH /Galaxy/*[@name] or //*[@name] OUTPUT <CelestialObje...