unit-calc

Tags numbers with unit types to enforce dimentional accuracy of calculations

It uses a plethora of GHC extentions, and surprisingly little code, to accomplish this goal at compile time. All the work's in src/Units/Internals.hs, but there are a couple extremely simple examples in src/Units/Examples.hs. It's probably most useful just for using GHCi as a calculator right now, but I might add more in the future.

A possible (future) setup to use the library:

• GHC extensions NoImplicitPrelude, TypeOperators
• import qualified Prelude if you really need to
• Import Units.Prelude and your preferred unit package

Unit packages: It'll be something like Units.SI, Units.Gaussian, Units.Common.{Metric,Imperial} where each exports (hopefully unique) identifiers for its units, as well as compound units.

I'm hoping for Units.Common to have simple commonly-used units like pounds, kilograms, feet, degrees Fahrenheit, and non-scientific things like conversions between kilos and pounds. Possibly currency also, or maybe in a separate module.

A brief to-do list:

• exponentiation -- I'll get to this eventually
• Implement Units.SI, Units.Gaussian, etc. modules
• generate stuff w/ TH:
  • Unit types (e.g. Meter), unit constants (e.g. meter) -- currently written out
  • Conversion units (e.g. centimetersPerYard, etc.) -- not there at the moment, probably more pressing than the first bullet