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In the Haskell source immediately below, :: can be read as "has type"; a -> b can be read as "is a function from a to b". (Thus the Haskell calc :: String -> [Float] can be read as "calc has type of a function from Strings to lists of Floats".)
String functions are used in computer programming languages to manipulate a string or query information about a string (some do both). Most programming languages that have a string datatype will have some string functions although there may be other low-level ways within each language to handle strings directly.
The first revision, named Haskell 2010, was announced in November 2009 [2] and published in July 2010. Haskell 2010 is an incremental update to the language, mostly incorporating several well-used and uncontroversial features previously enabled via compiler-specific flags. Hierarchical module names.
Many of the operators take other functions as arguments. These functions may be supplied in the form of a named method or anonymous function. The set of query operators defined by LINQ is exposed to the user as the Standard Query Operator (SQO) API. The query operators supported by the API are: [3] Select
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.
For instance, ignoring type classes which complicate the picture, 4 is a value of type Int, while [1, 2, 3] is a value of type [Int] (list of Ints). Therefore, Int and [Int] have kind , but so does any function type, for instance Int -> Bool or even Int -> Int -> Bool.
Hugs deviates from the Haskell 98 specification [2] in several minor ways. [3] For example, Hugs does not support mutually recursive modules. A list of differences exists. [4] The Hugs prompt is a Haskell read–eval–print loop (REPL). It accepts expressions for evaluation, but not module, type, or function definitions.
The following example of a SELECT query returns a list of expensive books. The query retrieves all rows from the Book table in which the price column contains a value greater than 100.00. The result is sorted in ascending order by title. The asterisk (*) in the select list indicates that all columns of the Book table should be included in the ...