vendor

vendor/github.com/samber/mo/state.go

@@ -0,0 +1,52 @@
+package mo
+
+func NewState[S any, A any](f func(state S) (A, S)) State[S, A] {
+	return State[S, A]{
+		run: f,
+	}
+}
+
+func ReturnState[S any, A any](x A) State[S, A] {
+	return State[S, A]{
+		run: func(state S) (A, S) {
+			return x, state
+		},
+	}
+}
+
+// State represents a function `(S) -> (A, S)`, where `S` is state, `A` is result.
+type State[S any, A any] struct {
+	run func(state S) (A, S)
+}
+
+// Run executes a computation in the State monad.
+func (s State[S, A]) Run(state S) (A, S) {
+	return s.run(state)
+}
+
+// Get returns the current state.
+func (s State[S, A]) Get() State[S, S] {
+	return State[S, S]{
+		run: func(state S) (S, S) {
+			return state, state
+		},
+	}
+}
+
+// Modify the state by applying a function to the current state.
+func (s State[S, A]) Modify(f func(state S) S) State[S, A] {
+	return State[S, A]{
+		run: func(state S) (A, S) {
+			return empty[A](), f(state)
+		},
+	}
+}
+
+// Put set the state.
+func (s State[S, A]) Put(state S) State[S, A] {
+	return State[S, A]{
+		run: func(state S) (A, S) {
+			return empty[A](), state
+		},
+	}
+}