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Haskell's main implementation is the Glasgow Haskell Compiler (GHC). Haskell's semantics are historically based on those of the Miranda programming language, which served to focus the efforts of the initial Haskell working group. [28]
This is a comparison of the features of the type systems and type checking of multiple programming languages.. Brief definitions A nominal type system means that the language decides whether types are compatible and/or equivalent based on explicit declarations and names.
In Haskell, the polymorphic function map :: (a -> b) -> [a] -> [b] is generalized to a polytypic function fmap :: Functor f => (a -> b) -> f a -> f b, which applies to any type belonging the Functor type class. The type constructor of lists [] can be defined as an instance of the Functor type class using the map function from the previous example:
The Glasgow Haskell Compiler (GHC) is a native or machine code compiler for the functional programming language Haskell. [5] It provides a cross-platform software environment for writing and testing Haskell code and supports many extensions, libraries , and optimisations that streamline the process of generating and executing code.
In a pure functional language, such as Haskell, all functions are without side effects, and state changes are only represented as functions that transform the state, which is explicitly represented as a first-class object in the program. Although pure functional languages are non-imperative, they often provide a facility for describing the ...
Notice that the type of the result can be regarded as everything past the first supplied argument. This is a consequence of currying, which is made possible by Haskell's support for first-class functions; this function requires two inputs where one argument is supplied and the function is "curried" to produce a function for the argument not supplied.
Mutability becomes an issue when trying to create interoperability between pure functional and procedural languages. Languages like Haskell have no mutable types, whereas C++ does not provide such rigorous guarantees. Many functional types when bridged to object oriented languages can not guarantee that the underlying objects won't be modified.
In the § More complex examples section above, calc is used in two senses, showing that there is a Haskell type class namespace and also a namespace for values: a Haskell type class for calc. The domain and range can be explicitly denoted in a Haskell type class. a Haskell value, formula, or expression for calc.