Added separate readme for the library.

kalk/README.md

@@ -0,0 +1,28 @@
+# kalk
+Kalk is a math parser library that supports user-defined variables and functions. An example of what it can parse:
+
+```
+f(x, y) = sum(1, 3, (2sin4/x!)^y) + cos(n deg)
+a = 3
+f(a, 2)
+```
+`>> 1.1899401098014355`
+
+## Features
+* Operators: +, -, \*, /, !
+* Groups: (), ⌈⌉, ⌋⌊
+* [Pre-defined functions and constants](https://github.com/PaddiM8/kalk/blob/master/kalk/src/prelude.rs)
+* User-defined functions and variables. `f(x, y) = xy`, `x = 5`
+* Understands fairly ambiguous syntax. Eg. `2sin50 + 2xy`
+
+## Usage
+```
+use kalk::parser;
+
+...
+let parser_context = parser::Context::new();
+assert_eq!(parser_context.eval("5*3").unwrap().unwrap(), 15);
+```
+
+## Compiling
+Make sure you have `diffutils` `gcc` `make` and `m4` installed.