monad-tree
This package provides monad instances for a rose-tree-like data structure Tree, allowing for the definition of non-deterministic computations that do not depend on a specific search procedure.
When not used as a monad for nondeterministic computation, Tree can also be used as a general purpose rose tree data structure.
For more information, see the documentation for the main Control.Monad.Tree module.
Related papers:
- The Algebra of Logic Programming, by Silvija Seres
- Typed Logical Variables in Haskell, by Koen Claessen and Peter Ljunglöf
- Lightweight Functional Logic Meta-Programming, Nada Amin et. al.