rextra/README.md

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.

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.

>>> 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

>>> saveDotAsPng "dfa_minimized.png" $ dfaToDot $ minimizeDfa a