4 files changed, 28 insertions, 23 deletions
diff --git a/src/main.rs b/src/main.rs
index 8984bf6..0a51789 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,7 +1,8 @@
-use particle_system::{Particle, ParticleSystem, Point, Solver, Vector};
+use particle_system::{Particle, ParticleSystem, Point, Vector};
+use solver::Solver;
 
-mod midpoint;
 mod particle_system;
+mod solver;
 
 fn main() {
     let dt = 0.01;
diff --git a/src/particle_system.rs b/src/particle_system.rs
index 52e6284..6f43c35 100644
--- a/src/particle_system.rs
+++ b/src/particle_system.rs
@@ -41,7 +41,3 @@ pub struct ParticleSystem {
     /// Simulation clock
     pub t: Scalar,
 }
-
-pub trait Solver {
-    fn step(&mut self, dt: Scalar);
-}
diff --git a/src/solver/midpoint.rs b/src/solver/midpoint.rs
new file mode 100644
index 0000000..c5a01c4
--- /dev/null
+++ b/src/solver/midpoint.rs
@@ -0,0 +1,18 @@
+use crate::particle_system::{ParticleSystem, Scalar};
+use super::{PhaseSpace, Solver};
+
+impl Solver for ParticleSystem {
+    fn step(&mut self, dt: Scalar) {
+        let mut state = self.collect_phase_space();
+
+        // Shift to the midpoint
+        self.scatter_phase_space(&&PhaseSpace {
+            0: state.0.clone() + self.compute_derivative().0 * dt / 2.0,
+        });
+
+        state.0 += self.compute_derivative().0 * dt;
+        self.scatter_phase_space(&state);
+
+        self.t += dt;
+    }
+}
diff --git a/src/midpoint.rs b/src/solver/mod.rs
index 1aa1de8..4a5fec5 100644
--- a/src/midpoint.rs
+++ b/src/solver/mod.rs
@@ -1,6 +1,8 @@
-use crate::particle_system::{ParticleSystem, Point, Scalar, Solver, Vector, N};
+use crate::particle_system::{ParticleSystem, Point, Scalar, Vector, N};
 use nalgebra::{Const, DVector, Dyn, Matrix, ViewStorage};
 
+mod midpoint;
+
 /// A vector of concatenated position and velocity components of each particle
 #[derive(Debug, Clone)]
 pub struct PhaseSpace(DVector<Scalar>);
@@ -70,26 +72,14 @@ impl ParticleSystem {
     }
 }
 
-impl Solver for ParticleSystem {
-    fn step(&mut self, dt: Scalar) {
-        let mut state = self.collect_phase_space();
-
-        // Shift to the midpoint
-        self.scatter_phase_space(&PhaseSpace {
-            0: state.0.clone() + self.compute_derivative().0 * dt / 2.0,
-        });
-
-        state.0 += self.compute_derivative().0 * dt;
-        self.scatter_phase_space(&state);
-
-        self.t += dt;
-    }
+pub trait Solver {
+    fn step(&mut self, dt: Scalar);
 }
 
 #[cfg(test)]
 mod tests {
-    use super::{ParticleSystem, PhaseSpace, Point, Scalar, Vector};
-    use crate::particle_system::{Particle, Solver};
+    use super::{ParticleSystem, PhaseSpace, Point, Scalar, Solver, Vector};
+    use crate::particle_system::Particle;
 
     #[test]
     fn test_collect_phase_space() {