Prepare files for making repository public

README.md

@@ -1 +1,36 @@
 # rextra
+
+At the moment, rextra can display DFAs and NFAs using Graphviz,
+convert between NFAs and DFAs, and minimize DFAs.
+
+The representation of DFAs and NFAs assumes an infinite alphabet:
+
+DFA states always contain a default transition (marked with `*` in the
+visualisations), which is taken if the current token doesn't appear in
+any of the other transitions.
+
+NFA transitions either apply to a set of tokens, or to all tokens
+*except* a specified set. In the visualisation, the character `Σ`
+denotes the alphabet of tokens.
+
+## Example
+
+This example minimizes the DFA shown on the
+[wikipedia article about DFA minimization](https://en.wikipedia.org/wiki/DFA_minimization).
+
+Transitions for the token `1` are specified explicitly (where
+necessary), while transitions for the token `0` are represented by the
+default transition marked with `*`.
+
+This ghci session shows the minimization of the DFA mentioned above.
+
+``` haskell
+>>> Just a = dfa [ ("a",[('1',"c")],"b"), ("b",[('1',"d")],"a"), ("c",[('1',"f")],"e"), ("d",[('1',"f")],"e"), ("e",[('1',"f")],"e"), ("f",[],"f") ] "a" ["c","d","e"]
+>>> saveDotAsPng "dfa.png" $ dfaToDot a
+```
+![](resources/minimization_example_dfa.png)
+``` haskell
+>>> saveDotAsPng "dfa_minimized.png" $ dfaToDot $ minimizeDfa a
+```
+![](resources/minimization_example_dfa_minimized.png)
+