[1] : The Free On-line Dictionary of Computing (27 SEP 03)

algebraic data type
     
         or "sum of products type" in functional
        programming, new types can be defined, each of which has one
        or more constructors.  such a type is known as an algebraic
        data type.  e.g. in haskell we can define a new type,
        "tree":
     
        	data tree = empty | leaf int | node tree tree
     
        with constructors "empty", "leaf" and "node".  the
        constructors can be used much like functions in that they can
        be partially applied to arguments of the appropriate type.
        for example, the leaf constructor has the functional type int
        -> tree.
     
        a constructor application cannot be reduced evaluated like a
        function application though since it is already in normal
        form.  functions which operate on algebraic data types can be
        defined using pattern matching:
     
        	depth :: tree -> int
        	depth empty	 = 0
        	depth leaf n	 = 1
        	depth node l r = 1 + max depth l depth r
     
        the most common algebraic data type is the list which has
        constructors nil and cons, written in haskell using the
        special syntax "" for nil and infix ":" for cons.
     
        special cases of algebraic types are product types only one
        constructor and enumeration types many constructors with
        no arguments.  algebraic types are one kind of constructed
        type i.e. a type formed by combining other types.
     
        an algebraic data type may also be an abstract data type
        adt if it is exported from a module without its
        constructors.  objects of such a type can only be manipulated
        using functions defined in the same module as the type
        itself.
     
        in set theory the equivalent of an algebraic data type is a
        discriminated union - a set whose elements consist of a tag
        equivalent to a constructor and an object of a type
        corresponding to the tag equivalent to the constructor
        arguments.
     
        1994-11-23
     
     
see also:
functional programming constructor haskell normal form pattern matching product type 
enumeration type constructed type abstract data type module set theory 
discriminated union 

Algebraic >> A Words
Algebraic, definition of term: Algebraic
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Data >> D Words
Data, definition of term: Data
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Data Glove >> D Words
Data Glove, definition of term: Data Glove
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Data Flow >> D Words
Data Flow, definition of term: Data Flow
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Data Mining >> D Words
Data Mining, definition of term: Data Mining
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Data Model >> D Words
Data Model, definition of term: Data Model
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Data Path >> D Words
Data Path, definition of term: Data Path
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Data Encryption >> D Words
Data Encryption, definition of term: Data Encryption
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Data Point >> D Words
Data Point, definition of term: Data Point
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Data Dictionary >> D Words
Data Dictionary, definition of term: Data Dictionary
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