Dimensional is a library providing data types for performing arithmetic with physical quantities and units. Information about the physical dimensions of the quantities/units is embedded in their types and the validity of operations is verified by the type checker at compile time. The boxing and unboxing of numerical values as quantities is done by multiplication and division with units. The library is designed to, as far as is practical, enforce/encourage best practices of unit usage.

A spin-off of dimensional is the numtype library which provides a type-level representation of integers. Numtype is a dependency of the dimensional library.

For documentation: see Conclusion and usage in the original announcement, the literate haskell code or the examples in the wiki.

The latest release can be installed with cabal install dimensional or downloaded from here or HackageDB.