@hackage type-level0.2.4

type-level: Type-level programming library

DESCRIPTION

This library permits performing computations on the type-level. Type-level functions are implemented using functional dependencies of multi parameter type classes.

To date, Booleans and Numerals (Naturals and Positives) are supported. With regard to Numerals, there is support for common arithmetic operations (addition, substraction, multiplication, division, exponientation, logarithm, maximum, comparison, GCD) over natural numbers (using a decimal representation to make compile-time errors friendlier).

Although making use of type-level computations might seem devious and obfuscated at first sight, it is indeed useful in practice to implement lightweight dependent types such us number-parameterized types (e.g. an array type parameterized by the array's size or a modular group type Zn parameterized by the modulus).

Here is a tutorial on type-level numerals and how to use them to implement numerically-parameterized vectors: http://www.ict.kth.se/org/ict/ecs/sam/projects/forsyde/www/files/tutorial/tutorial.html#FSVec

DEPENDENCIES

type-level depends on GHC (due to the use of Multiparameter Type Classes and infix type constructors) and Template Haskell

INSTALLATION

to install globally, for the whole system (requires admin permissions):

$ ./Setup.hs configure $ ./Setup.hs build $ ./Setup.hs haddock # generate documentation, optional, # requires Haddock > 2.0 due to the use of TH $ ./Setup.hs install

to install locally and just for your own user:

$ ./Setup.hs configure --prefix=The/selected/local/directory $ ./Setup.hs build $ ./Setup.hs haddock # generate documentation, optional, # requires Haddock > 2.0 due to the use of TH

$ ./Setup.hs install --user