initial commit

src/glemt.gleam

@@ -0,0 +1,65 @@
+import gleam/list
+import gleam/string
+import gleam/set.{type Set}
+import gleam/io
+
+//pub type State {
+//  State(Int)
+//}
+
+pub type State = Int
+
+//pub type AlphabetChar {
+//  AlphabetChar(String)
+//}
+
+pub type AlphabetChar = String
+
+pub type NFAError {
+  NoTransition
+}
+
+pub type NFA {
+  NFA(states: Set(State), alphabet: Set(AlphabetChar), transition_func: fn(State, AlphabetChar) -> Result(State, NFAError), init_state: State, accepting_states: Set(State))
+}
+
+//pub type DFAViolation {
+//  NotAllTransitionsDefined
+//  MultiplePossibleTransitions
+//}
+
+pub fn check_string(automaton: NFA, input: String) -> Bool {
+  let result = input
+  |> string.to_graphemes
+  |> list.try_fold(automaton.init_state, automaton.transition_func)
+
+  case result {
+    Ok(state) -> set.contains(automaton.accepting_states, state)
+    Error(_) -> False
+  }
+}
+
+pub fn even_a() -> NFA {
+  let states = set.from_list([0, 1])
+  let alphabet = set.from_list(["a"])
+  let transition_func = fn (state: State, char: AlphabetChar) -> Result(State, NFAError) {
+    case state, char {
+      0, "a" -> Ok(1)
+      1, "a" -> Ok(0)
+      _, _ -> Error(NoTransition)
+    }
+  }
+  let init_state = 0
+  let accepting_states = set.from_list([0])
+  NFA(states:, alphabet:, transition_func:, init_state:, accepting_states:)
+}
+
+pub fn main() {
+  io.println("Hello from glemt!")
+
+  let automaton = even_a()
+  io.debug(check_string(automaton, ""))
+  io.debug(check_string(automaton, "a"))
+  io.debug(check_string(automaton, "aa"))
+  io.debug(check_string(automaton, "aaab"))
+}