refactor out modules to files

src/labelgen.rs

@@ -0,0 +1,35 @@
+use crate::state::WithState;
+
+// Generate a next label
+pub trait States {
+    type Item;
+    fn init() -> Self::Item;
+    fn next<'c, Value>(f: impl FnOnce(Self::Item) -> Value + 'c) -> WithState<'c, Value, Self::Item>;
+}
+
+pub struct IntCounter;
+
+impl States for IntCounter
+{
+    type Item = i32;
+    
+    fn init() -> i32 { 0 }
+    
+    fn next<'c, Value>(f: impl FnOnce(i32) -> Value + 'c) -> WithState<'c, Value, i32> {
+	WithState::of(move |n| { (f(n), n + 1) })
+    }
+}
+
+
+pub struct StrCat;
+
+impl States for StrCat
+{
+    type Item = String;
+
+    fn init() -> String { "a".to_string() }
+
+    fn next<'c, Value>(f: impl FnOnce(Self::Item) -> Value + 'c) -> WithState<'c, Value, Self::Item> {
+	WithState::of(move |n: String| { let s = n.clone(); (f(n), format!("{}a", s)) })
+    }
+}

src/main.rs

@@ -1,79 +1,7 @@
-mod state {
+mod state;
-    // State monad
+mod labelgen;
-    pub struct WithState<'c, Value, State>(Box<dyn FnOnce(State) -> (Value, State) + 'c>);
 
-    impl <'c, Value, State> WithState<'c, Value, State> {
+use labelgen::{IntCounter, States};
-	pub fn of(f: impl FnOnce(State) -> (Value, State) + 'c) -> WithState<'c, Value, State> {
-	    WithState(Box::new(f))
-	}
-	
-	pub fn run(self, s: State) -> (Value, State) {
-	    self.0(s)
-	}
-
-	pub fn bind<'cn, NewValue>(self, f: impl FnOnce(Value) -> WithState<'cn, NewValue, State> + 'cn) -> WithState<'cn, NewValue, State>
-	where 'c: 'cn, State : 'cn, Value : 'cn {
-	    WithState::<'cn, NewValue, State>::of(move |n| {
-		let (x,sp) = self.run(n);
-		f(x).run(sp)
-	    })
-	}
-
-	pub fn zip<'cn, NewValue>(self, st: WithState<'cn, NewValue, State>) -> WithState<'cn, (Value,NewValue), State>
-	where 'c: 'cn, State: 'cn, Value: 'cn, NewValue: 'cn {
-	    self.bind(|aa| st.map(|bb| (aa,bb)))
-	}
-
-	pub fn map<'cn, NewValue>(self, f: impl FnOnce(Value) -> NewValue + 'cn) -> WithState<'cn, NewValue, State>
-	where 'c: 'cn, State : 'cn, Value : 'cn {
-	    WithState::<'cn, NewValue, State>::of(move |n| {
-		let (x, sp) = self.run(n);
-		( f(x), sp )
-	    })
-	}
-    }
-}
-
-
-mod labelgenerators {
-    use super::state::WithState;
-
-    // Generate a next label
-    pub trait States {
-	type Item;
-	fn init() -> Self::Item;
-	fn next<'c, Value>(f: impl FnOnce(Self::Item) -> Value + 'c) -> WithState<'c, Value, Self::Item>;
-    }
-
-    pub struct IntCounter;
-
-    impl States for IntCounter
-    {
-	type Item = i32;
-	
-	fn init() -> i32 { 0 }
-	
-	fn next<'c, Value>(f: impl FnOnce(i32) -> Value + 'c) -> WithState<'c, Value, i32> {
-	    WithState::of(move |n| { (f(n), n + 1) })
-	}
-    }
-
-
-    pub struct StrCat;
-
-    impl States for StrCat
-    {
-	type Item = String;
-
-	fn init() -> String { "a".to_string() }
-
-	fn next<'c, Value>(f: impl FnOnce(Self::Item) -> Value + 'c) -> WithState<'c, Value, Self::Item> {
-	    WithState::of(move |n: String| { let s = n.clone(); (f(n), format!("{}a", s)) })
-	}
-    }
-}
-
-use labelgenerators::*;
 use state::WithState;
 
 // Tree

src/state.rs

@@ -0,0 +1,33 @@
+// State monad
+pub struct WithState<'c, Value, State>(Box<dyn FnOnce(State) -> (Value, State) + 'c>);
+
+impl <'c, Value, State> WithState<'c, Value, State> {
+    pub fn of(f: impl FnOnce(State) -> (Value, State) + 'c) -> WithState<'c, Value, State> {
+	WithState(Box::new(f))
+    }
+    
+    pub fn run(self, s: State) -> (Value, State) {
+	self.0(s)
+    }
+
+    pub fn bind<'cn, NewValue>(self, f: impl FnOnce(Value) -> WithState<'cn, NewValue, State> + 'cn) -> WithState<'cn, NewValue, State>
+    where 'c: 'cn, State : 'cn, Value : 'cn {
+	WithState::<'cn, NewValue, State>::of(move |n| {
+	    let (x,sp) = self.run(n);
+	    f(x).run(sp)
+	})
+    }
+
+    pub fn zip<'cn, NewValue>(self, st: WithState<'cn, NewValue, State>) -> WithState<'cn, (Value,NewValue), State>
+    where 'c: 'cn, State: 'cn, Value: 'cn, NewValue: 'cn {
+	self.bind(|aa| st.map(|bb| (aa,bb)))
+    }
+
+    pub fn map<'cn, NewValue>(self, f: impl FnOnce(Value) -> NewValue + 'cn) -> WithState<'cn, NewValue, State>
+    where 'c: 'cn, State : 'cn, Value : 'cn {
+	WithState::<'cn, NewValue, State>::of(move |n| {
+	    let (x, sp) = self.run(n);
+	    ( f(x), sp )
+	})
+    }
+}