An XQuery 3.0 library for defining algebraic data types, and performing structural pattern matching on them. This can be used to define complex data structures and the operations on them.

Author: John Snelson June 28, 2012

Version: 0.1

• Functions: declare#1, declare#2, type#1, describe#1, match#2, match#3, match#4, match#5, match#6, match#7, match#8, match#9, match#10, match#11

declare($decl as element()
) as  function(*)*

Returns a sequence of constructor functions for the XML type description passed in as an argument. One constructor function is returned for each of the sub-types described. The constructor functions can be called to construct an instance of the type, passing in the values required the specific sub-type being created.

An example of an XML description is:

 <Maybe>
   <Nothing/>
   <Just><data:Sequence/></Just>
 </Maybe>
 

This defines a type named "Maybe", with two sub-types named "Nothing" and "Just". The "Nothing" constructor function takes no arguments, and store no additional data. The "Just" constructor function takes a single argument which is an arbitrary sequence. Passing this type description to this function will return two constructor functions, one for each sub-type.

Another example of an XML description is:

 <Tree>
   <Empty/>
   <Leaf><data:Sequence/></Leaf>
   <Node><Tree/><Tree/></Node>
 </Tree>
 

This defines a type named "Tree", with three sub-types named "Empty", "Leaf", and "Node". The "Node" constructor function takes two arguments, each of which will be type checked as a "Tree" object during construction.

• $decl as element(): An XML description of an algebraic data type.

• function(*)*: A sequence of constructor functions for the given algebraic type description.

declare($decl as element(),$type-check as xs:boolean
) as  function(*)*

Returns a sequence of constructor functions for the XML type description passed in as an argument. One constructor function is returned for each of the sub-types described. The constructor functions can be called to construct an instance of the type, passing in the values required the specific sub-type being created.

An example of an XML description is:

 <Maybe>
   <Nothing/>
   <Just><data:Sequence/></Just>
 </Maybe>
 

This defines a type named "Maybe", with two sub-types named "Nothing" and "Just". The "Nothing" constructor function takes no arguments, and store no additional data. The "Just" constructor function takes a single argument which is an arbitrary sequence. Passing this type description to this function will return two constructor functions, one for each sub-type.

Another example of an XML description is:

 <Tree>
   <Empty/>
   <Leaf><data:Sequence/></Leaf>
   <Node><Tree/><Tree/></Node>
 </Tree>
 

This defines a type named "Tree", with three sub-types named "Empty", "Leaf", and "Node". The "Node" constructor function takes two arguments, each of which will be type checked as a "Tree" object during construction.

• $decl as element(): An XML description of an algebraic data type.

• $type-check as xs:boolean: Setting this argument to false turns off type checking during value construction, which can speed up data structure creation.

• function(*)*: A sequence of constructor functions for the given algebraic type description.

type($v as item()
) as  element()

Returns the type of the value - that is, the child node in the XML type description that represents this value.

• $v as item(): A value, which must have been created by this library.

• element(): The description element representing the type of the value.

describe($v
) as  xs:string

Returns a string serialization of the structure of the values. Non-algebraic types are serialized using the fn:string() function.

• $v: A sequence of values, which must have been created by this library.

• xs:string: The serialization of the values.

match(
  $v as item(),
  $f1 as function(*)
)

Performs structural pattern matching against the value. The pattern matching works by calling the function passed in in the same position as the sub-type of the value. Therefore the number of functions passed in as arguments must equal the number of sub-types of the value, and each function should have the same arity as its corresponding sub-type contains values.

• $v as item(): A value, which must have been created by this library.

• $f1 as function(*): A function, which is called with the values from the first sub-type of the type.

match(
  $v as item(),
  $f1 as function(*),
  $f2 as function(*)
)

Performs structural pattern matching against the value. The pattern matching works by calling the function passed in in the same position as the sub-type of the value. Therefore the number of functions passed in as arguments must equal the number of sub-types of the value, and each function should have the same arity as its corresponding sub-type contains values.

• $v as item(): A value, which must have been created by this library.

• $f1 as function(*): A function, which is called with the values from the first sub-type of the type.

• $f2 as function(*): A function, which is called with the values from the second sub-type of the type.

match(
  $v as item(),
  $f1 as function(*),
  $f2 as function(*),
  $f3 as function(*)
)

Performs structural pattern matching against the value. The pattern matching works by calling the function passed in in the same position as the sub-type of the value. Therefore the number of functions passed in as arguments must equal the number of sub-types of the value, and each function should have the same arity as its corresponding sub-type contains values.

• $v as item(): A value, which must have been created by this library.

• $f1 as function(*): A function, which is called with the values from the first sub-type of the type.

• $f2 as function(*): A function, which is called with the values from the second sub-type of the type.

• $f3 as function(*): A function, which is called with the values from the third sub-type of the type.

match(
  $v as item(),
  $f1 as function(*),
  $f2 as function(*),
  $f3 as function(*),
  $f4 as function(*)
)

Performs structural pattern matching against the value. The pattern matching works by calling the function passed in in the same position as the sub-type of the value. Therefore the number of functions passed in as arguments must equal the number of sub-types of the value, and each function should have the same arity as its corresponding sub-type contains values.

• $v as item(): A value, which must have been created by this library.

• $f1 as function(*): A function, which is called with the values from the first sub-type of the type.

• $f2 as function(*): A function, which is called with the values from the second sub-type of the type.

• $f3 as function(*): A function, which is called with the values from the third sub-type of the type.

• $f4 as function(*): A function, which is called with the values from the fourth sub-type of the type.

match(
  $v as item(),
  $f1 as function(*),
  $f2 as function(*),
  $f3 as function(*),
  $f4 as function(*),
  $f5 as function(*)
)

Performs structural pattern matching against the value. The pattern matching works by calling the function passed in in the same position as the sub-type of the value. Therefore the number of functions passed in as arguments must equal the number of sub-types of the value, and each function should have the same arity as its corresponding sub-type contains values.

• $v as item(): A value, which must have been created by this library.

• $f1 as function(*): A function, which is called with the values from the first sub-type of the type.

• $f2 as function(*): A function, which is called with the values from the second sub-type of the type.

• $f3 as function(*): A function, which is called with the values from the third sub-type of the type.

• $f4 as function(*): A function, which is called with the values from the fourth sub-type of the type.

• $f5 as function(*): A function, which is called with the values from the fifth sub-type of the type.

match(
  $v as item(),
  $f1 as function(*),
  $f2 as function(*),
  $f3 as function(*),
  $f4 as function(*),
  $f5 as function(*),
  $f6 as function(*)
)

Performs structural pattern matching against the value. The pattern matching works by calling the function passed in in the same position as the sub-type of the value. Therefore the number of functions passed in as arguments must equal the number of sub-types of the value, and each function should have the same arity as its corresponding sub-type contains values.

• $v as item(): A value, which must have been created by this library.

• $f1 as function(*): A function, which is called with the values from the first sub-type of the type.

• $f2 as function(*): A function, which is called with the values from the second sub-type of the type.

• $f3 as function(*): A function, which is called with the values from the third sub-type of the type.

• $f4 as function(*): A function, which is called with the values from the fourth sub-type of the type.

• $f5 as function(*): A function, which is called with the values from the fifth sub-type of the type.

• $f6 as function(*): A function, which is called with the values from the sixth sub-type of the type.

match(
  $v as item(),
  $f1 as function(*),
  $f2 as function(*),
  $f3 as function(*),
  $f4 as function(*),
  $f5 as function(*),
  $f6 as function(*),
  $f7 as function(*)
)

Performs structural pattern matching against the value. The pattern matching works by calling the function passed in in the same position as the sub-type of the value. Therefore the number of functions passed in as arguments must equal the number of sub-types of the value, and each function should have the same arity as its corresponding sub-type contains values.

• $v as item(): A value, which must have been created by this library.

• $f1 as function(*): A function, which is called with the values from the first sub-type of the type.

• $f2 as function(*): A function, which is called with the values from the second sub-type of the type.

• $f3 as function(*): A function, which is called with the values from the third sub-type of the type.

• $f4 as function(*): A function, which is called with the values from the fourth sub-type of the type.

• $f5 as function(*): A function, which is called with the values from the fifth sub-type of the type.

• $f6 as function(*): A function, which is called with the values from the sixth sub-type of the type.

• $f7 as function(*): A function, which is called with the values from the seventh sub-type of the type.

match(
  $v as item(),
  $f1 as function(*),
  $f2 as function(*),
  $f3 as function(*),
  $f4 as function(*),
  $f5 as function(*),
  $f6 as function(*),
  $f7 as function(*),
  $f8 as function(*)
)

Performs structural pattern matching against the value. The pattern matching works by calling the function passed in in the same position as the sub-type of the value. Therefore the number of functions passed in as arguments must equal the number of sub-types of the value, and each function should have the same arity as its corresponding sub-type contains values.

• $v as item(): A value, which must have been created by this library.

• $f1 as function(*): A function, which is called with the values from the first sub-type of the type.

• $f2 as function(*): A function, which is called with the values from the second sub-type of the type.

• $f3 as function(*): A function, which is called with the values from the third sub-type of the type.

• $f4 as function(*): A function, which is called with the values from the fourth sub-type of the type.

• $f5 as function(*): A function, which is called with the values from the fifth sub-type of the type.

• $f6 as function(*): A function, which is called with the values from the sixth sub-type of the type.

• $f7 as function(*): A function, which is called with the values from the seventh sub-type of the type.

• $f8 as function(*): A function, which is called with the values from the eighth sub-type of the type.

match(
  $v as item(),
  $f1 as function(*),
  $f2 as function(*),
  $f3 as function(*),
  $f4 as function(*),
  $f5 as function(*),
  $f6 as function(*),
  $f7 as function(*),
  $f8 as function(*),
  $f9 as function(*)
)

Performs structural pattern matching against the value. The pattern matching works by calling the function passed in in the same position as the sub-type of the value. Therefore the number of functions passed in as arguments must equal the number of sub-types of the value, and each function should have the same arity as its corresponding sub-type contains values.

• $v as item(): A value, which must have been created by this library.

• $f1 as function(*): A function, which is called with the values from the first sub-type of the type.

• $f2 as function(*): A function, which is called with the values from the second sub-type of the type.

• $f3 as function(*): A function, which is called with the values from the third sub-type of the type.

• $f4 as function(*): A function, which is called with the values from the fourth sub-type of the type.

• $f5 as function(*): A function, which is called with the values from the fifth sub-type of the type.

• $f6 as function(*): A function, which is called with the values from the sixth sub-type of the type.

• $f7 as function(*): A function, which is called with the values from the seventh sub-type of the type.

• $f8 as function(*): A function, which is called with the values from the eighth sub-type of the type.

• $f9 as function(*): A function, which is called with the values from the ninth sub-type of the type.

match(
  $v as item(),
  $f1 as function(*),
  $f2 as function(*),
  $f3 as function(*),
  $f4 as function(*),
  $f5 as function(*),
  $f6 as function(*),
  $f7 as function(*),
  $f8 as function(*),
  $f9 as function(*),
  $f10 as function(*)
)

Performs structural pattern matching against the value. The pattern matching works by calling the function passed in in the same position as the sub-type of the value. Therefore the number of functions passed in as arguments must equal the number of sub-types of the value, and each function should have the same arity as its corresponding sub-type contains values.

• $v as item(): A value, which must have been created by this library.

• $f1 as function(*): A function, which is called with the values from the first sub-type of the type.0: A function, which is called with the values from the tenth sub-type of the type.

• $f2 as function(*): A function, which is called with the values from the second sub-type of the type.

• $f3 as function(*): A function, which is called with the values from the third sub-type of the type.

• $f4 as function(*): A function, which is called with the values from the fourth sub-type of the type.

• $f5 as function(*): A function, which is called with the values from the fifth sub-type of the type.

• $f6 as function(*): A function, which is called with the values from the sixth sub-type of the type.

• $f7 as function(*): A function, which is called with the values from the seventh sub-type of the type.

• $f8 as function(*): A function, which is called with the values from the eighth sub-type of the type.

• $f9 as function(*): A function, which is called with the values from the ninth sub-type of the type.

• $f10 as function(*): A function, which is called with the values from the tenth sub-type of the type.

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