36 lines
1.3 KiB
Markdown
36 lines
1.3 KiB
Markdown
# 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
|
|
```
|
|
|
|
``` haskell
|
|
>>> saveDotAsPng "dfa_minimized.png" $ dfaToDot $ minimizeDfa a
|
|
```
|
|
|
|
|