# Difference between revisions of "Stanamic typing"

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+ | "We describe a datatype of polymorphic balanced binary trees: AVL trees. | ||

+ | The trees are polymorphic: the values in different nodes may have | ||

+ | different type. The trees are balanced: for each non-leaf node, the | ||

+ | heights of its two children can differ at most by one. Here, by | ||

+ | definition the height of a node is 1 + max of the heights of its | ||

+ | children. A leaf node has the height of 0. | ||

+ | The main feature of the present approach is a blended static and dynamic | ||

+ | enforcement of the balancing constraint. The function make_node | ||

+ | verifies the balancing constraint at compile time -- if it can. If the | ||

+ | static check is not possible, the function delays the check till the | ||

+ | run-time" | ||

+ | |||

+ | [http://okmij.org/ftp/Haskell/types.html#stanamic-AVL Polymorphic stanamically balanced AVL trees] | ||

+ | |||

+ | [[Category:Idioms]] |

## Latest revision as of 15:19, 6 February 2021

"We describe a datatype of polymorphic balanced binary trees: AVL trees. The trees are polymorphic: the values in different nodes may have different type. The trees are balanced: for each non-leaf node, the heights of its two children can differ at most by one. Here, by definition the height of a node is 1 + max of the heights of its children. A leaf node has the height of 0.

The main feature of the present approach is a blended static and dynamic enforcement of the balancing constraint. The function make_node verifies the balancing constraint at compile time -- if it can. If the static check is not possible, the function delays the check till the run-time"