A calculator supporting units of measurement, written in Haskell.
Run it by installing the Haskell Platform, cloning this repo, and running cabal run.
It can do conversions between units of measurement:
> 60 mph @ m/s
26.8224 m/s
> lightYear @ km
9.454254955488e12 km
Defining new units is easy:
> unit pound/pounds(lb) = 0.45359 kg
> 100 lb @ kg
45.359 kg
> 100 kg @ lb
220.46341409643068 lb
It also supports variables:
> lightSpeed = 299792458 m/s
2.99792458e8 m/s
> lightSpeed @ mph
6.706166293843952e8 mph
> lightSpeed * 1 nanosecond @ meters
0.29979245800000004 meters
It supports bits and bytes, and the corresponding prefixes:
> 1 @ bits/byte
8.0 bits/byte
> 1 MB @ bytes
1000000.0 bytes
> 1 MiB @ bytes
1048576.0 bytes
It also supports functions:
> f = \x,y -> x+y
> f 5 4
9.0
The standard library currently includes definitions of most SI units and a few others.
Units and variables defined in the REPL are automatically saved. Files are also supported (through the load command), but the REPL is the primary interface.
These can only be used in the REPL, not in a file.
> exit
Self-explanatory.
> load <filename>
Loads a file and runs every line in it.
Operator precedence is a bit strange compared to most languages. It matters whether there's spaces around an operator. For example:
> 2 + 3 * 4
14.0
> 2+3 * 4
20.0
Operator precedence works this way so that expressions like the following work as expected:
> 2 m^2
2.0 m^2.0
If operator prededence worked as in most languages, this would unexpectedly be parsed as (2 m)^2 and return 4.0 m^2.0.
There's three commands for defining units: unit, si-unit, and bin-unit. They have the same syntax, but si-unit automatically generates versions of the unit with SI prefixes, and bin-unit additionally generates binary prefixes. For instance, si-unit meter/meters(m) will automatically define the units centimeter, cm, kilometer, km, etc.
Units and variables are case-sensitive. For instance, 5 KM won't work.