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: https://forsyde.ict.kth.se/trac/wiki/ForSyDe/Haskell/ForSyDeTutorial#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