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C# 3.0 introduced type inference, allowing the type specifier of a variable declaration to be replaced by the keyword var, if its actual type can be statically determined from the initializer. This reduces repetition, especially for types with multiple generic type-parameters, and adheres more closely to the DRY principle.
List comprehension is a syntactic construct available in some programming languages for creating a list based on existing lists. It follows the form of the mathematical set-builder notation (set comprehension) as distinct from the use of map and filter functions.
List comprehension – C# 3 LINQ; Tuples – .NET Framework 4.0 but it becomes popular when C# 7.0 introduced a new tuple type with language support [104] Nested functions – C# 7.0 [104] Pattern matching – C# 7.0 [104] Immutability – C# 7.2 readonly struct C# 9 record types [105] and Init only setters [106]
Here, the list [0..] represents , x^2>3 represents the predicate, and 2*x represents the output expression.. List comprehensions give results in a defined order (unlike the members of sets); and list comprehensions may generate the members of a list in order, rather than produce the entirety of the list thus allowing, for example, the previous Haskell definition of the members of an infinite list.
Class templates are often used to make generic containers. For example, the STL has a linked list container. To make a linked list of integers, one writes list<int>. A list of strings is denoted list<string>. A list has a set of standard functions associated with it, that work for any compatible parameterizing types.
The identity function is a particularly extreme example, but many other functions also benefit from parametric polymorphism. For example, an a p p e n d {\displaystyle {\mathsf {append}}} function that concatenates two lists does not inspect the elements of the list, only the list structure itself.
Languages with first-class functions have function types like "a function expecting a Cat and returning an Animal" (written cat-> animal in OCaml syntax or Func < Cat, Animal > in C# syntax). Those languages also need to specify when one function type is a subtype of another—that is, when it is safe to use a function of one type in a context ...
String functions common to many languages are listed below, including the different names used. The below list of common functions aims to help programmers find the equivalent function in a language. Note, string concatenation and regular expressions are handled in separate pages. Statements in guillemets (« … ») are optional.