diff --git a/FUTURE.md b/FUTURE.md
index 4b886ad..30514b1 100644
--- a/FUTURE.md
+++ b/FUTURE.md
@@ -14,7 +14,6 @@ This is a list of feature ideas for the future.
 - Improve or replace the drum sounds in the `sound` module.
 - Real-time safe sound server that uses `cpal`. It could have a static set of read/write channels for rendering audio, including hardware channels.
 - Conversion of graphs into a graphical form. Format associative operator chains appropriately.
-- Interpreter for simple FunDSP expressions.
 - Expand `README.md` into a book.
 - Time stretching / pitch shifting algorithm.
 - FFT convolution engine and HRTF support.
diff --git a/README.md b/README.md
index dcb08be..5969dde 100644
--- a/README.md
+++ b/README.md
@@ -40,6 +40,8 @@ To discuss FunDSP and other topics, come hang out with us at the
 [bevy_fundsp](https://github.com/harudagondi/bevy_fundsp) integrates FunDSP into
 the [Bevy](https://bevyengine.org/) game engine.
 
+[lapis](https://github.com/tomara-x/lapis) is an interpreter for FunDSP expressions.
+
 [midi_fundsp](https://github.com/gjf2a/midi_fundsp) enables the easy creation
 of live synthesizer software using FunDSP for synthesis.
 
@@ -1196,6 +1198,10 @@ The type parameters in the table refer to the hacker preludes.
 | `pipei::<U, _, _>(f)`  |   `f`   |   `f`   | Chain `U` nodes from indexed generator `f`. |
 | `pipef::<U, _, _>(f)`  |   `f`   |   `f`   | Chain `U` nodes from fractional generator `f`. |
 | `pluck(f, gain, damping)` | 1 (excitation) | 1 | [Karplus-Strong](https://en.wikipedia.org/wiki/Karplus%E2%80%93Strong_string_synthesis) plucked string oscillator with frequency `f` Hz, `gain` per second (`gain` <= 1) and high frequency `damping` in 0...1. |
+| `poly_saw()`           | 1 (frequency) | 1 | Bandlimited saw wave oscillator. |
+| `poly_saw_hz(f)`       |    -    |    1    | Bandlimited saw wave oscillator with frequency `f` Hz. |
+| `poly_square()`        | 1 (frequency) | 1 | Bandlimited square wave oscillator. |
+| `poly_square_hz(f)`    |    -    |    1    | Bandlimited square wave oscillator with frequency `f` Hz. |
 | `product(x, y)`        | `x + y` | `x = y` | Multiply nodes `x` and `y`. Same as `x * y`. |
 | `pulse()`              | 2 (frequency, duty cycle) | 1 | Bandlimited pulse wave with duty cycle in 0...1. |
 | `ramp()`               | 1 (frequency) | 1 | Non-bandlimited ramp (sawtooth) wave in 0...1. |
diff --git a/examples/keys.rs b/examples/keys.rs
index 21ff304..982ae5e 100644
--- a/examples/keys.rs
+++ b/examples/keys.rs
@@ -20,6 +20,8 @@ enum Waveform {
     Pulse,
     Pluck,
     Noise,
+    PolySaw,
+    PolySquare,
 }
 
 #[derive(Debug, PartialEq)]
@@ -262,12 +264,14 @@ impl eframe::App for State {
                 ui.selectable_value(&mut self.waveform, Waveform::Square, "Square");
                 ui.selectable_value(&mut self.waveform, Waveform::Triangle, "Triangle");
                 ui.selectable_value(&mut self.waveform, Waveform::Organ, "Organ");
+                ui.selectable_value(&mut self.waveform, Waveform::Hammond, "Hammond");
             });
             ui.horizontal(|ui| {
-                ui.selectable_value(&mut self.waveform, Waveform::Hammond, "Hammond");
                 ui.selectable_value(&mut self.waveform, Waveform::Pulse, "Pulse");
                 ui.selectable_value(&mut self.waveform, Waveform::Pluck, "Pluck");
                 ui.selectable_value(&mut self.waveform, Waveform::Noise, "Noise");
+                ui.selectable_value(&mut self.waveform, Waveform::PolySaw, "PolySaw");
+                ui.selectable_value(&mut self.waveform, Waveform::PolySquare, "PolySquare");
             });
             ui.separator();
 
@@ -479,6 +483,8 @@ impl eframe::App for State {
                                 >> resonator()
                                 >> shape(Adaptive::new(0.1, Atan(0.05))) * 0.5,
                         )),
+                        Waveform::PolySaw => Net::wrap(Box::new(pitch >> poly_saw() * 0.06)),
+                        Waveform::PolySquare => Net::wrap(Box::new(pitch >> poly_square() * 0.06)),
                     };
                     let filter = match self.filter {
                         Filter::None => Net::wrap(Box::new(pass())),
diff --git a/src/hacker.rs b/src/hacker.rs
index bb29716..ce1ed3b 100644
--- a/src/hacker.rs
+++ b/src/hacker.rs
@@ -2655,3 +2655,29 @@ pub fn fresonator_hz<S: Shape>(
 ) -> An<FixedFbBiquad<f64, ResonatorBiquad<f64>, S>> {
     super::prelude::fresonator_hz(shape, center as f64, q as f64)
 }
+
+/// PolyBLEP saw wave oscillator. A fast bandlimited saw wave algorithm.
+/// - Input 0: frequency (Hz)
+/// - Output 0: saw wave
+pub fn poly_saw() -> An<PolySaw<f64>> {
+    An(PolySaw::new())
+}
+
+/// PolyBLEP saw wave oscillator at `f` Hz. A fast bandlimited saw wave algorithm.
+/// - Output 0: saw wave
+pub fn poly_saw_hz(f: f32) -> An<Pipe<Constant<U1>, PolySaw<f64>>> {
+    dc(f) >> poly_saw()
+}
+
+/// PolyBLEP square wave oscillator. A fast bandlimited square wave algorithm.
+/// - Input 0: frequency (Hz)
+/// - Output 0: square wave
+pub fn poly_square() -> An<PolySquare<f64>> {
+    An(PolySquare::new())
+}
+
+/// PolyBLEP square wave oscillator at `f` Hz. A fast bandlimited square wave algorithm.
+/// - Output 0: square wave
+pub fn poly_square_hz(f: f32) -> An<Pipe<Constant<U1>, PolySquare<f64>>> {
+    dc(f) >> poly_square()
+}
diff --git a/src/hacker32.rs b/src/hacker32.rs
index d211388..c80905d 100644
--- a/src/hacker32.rs
+++ b/src/hacker32.rs
@@ -2655,3 +2655,29 @@ pub fn fresonator_hz<S: Shape>(
 ) -> An<FixedFbBiquad<f32, ResonatorBiquad<f32>, S>> {
     super::prelude::fresonator_hz(shape, center, q)
 }
+
+/// PolyBLEP saw wave oscillator. A fast bandlimited saw wave algorithm.
+/// - Input 0: frequency (Hz)
+/// - Output 0: saw wave
+pub fn poly_saw() -> An<PolySaw<f32>> {
+    An(PolySaw::new())
+}
+
+/// PolyBLEP saw wave oscillator at `f` Hz. A fast bandlimited saw wave algorithm.
+/// - Output 0: saw wave
+pub fn poly_saw_hz(f: f32) -> An<Pipe<Constant<U1>, PolySaw<f32>>> {
+    dc(f) >> poly_saw()
+}
+
+/// PolyBLEP square wave oscillator. A fast bandlimited square wave algorithm.
+/// - Input 0: frequency (Hz)
+/// - Output 0: square wave
+pub fn poly_square() -> An<PolySquare<f32>> {
+    An(PolySquare::new())
+}
+
+/// PolyBLEP square wave oscillator at `f` Hz. A fast bandlimited square wave algorithm.
+/// - Output 0: square wave
+pub fn poly_square_hz(f: f32) -> An<Pipe<Constant<U1>, PolySquare<f32>>> {
+    dc(f) >> poly_square()
+}
diff --git a/src/oscillator.rs b/src/oscillator.rs
index ce8605a..cf67d06 100644
--- a/src/oscillator.rs
+++ b/src/oscillator.rs
@@ -455,7 +455,7 @@ impl<F: Float> Ramp<F> {
 }
 
 impl<F: Float> AudioNode for Ramp<F> {
-    const ID: u64 = 21;
+    const ID: u64 = 94;
     type Inputs = typenum::U1;
     type Outputs = typenum::U1;
 
@@ -487,3 +487,160 @@ impl<F: Float> AudioNode for Ramp<F> {
         super::signal::Routing::Arbitrary(0.0).route(input, self.outputs())
     }
 }
+
+/// PolyBLEP function with phase `t` in 0...1 and phase increment `dt`.
+fn polyblep<F: Float>(t: F, dt: F) -> F {
+    if t < dt {
+        let z = t / dt;
+        z + z - z * z - F::one()
+    } else if t > F::one() - dt {
+        let z = (t - F::one()) / dt;
+        z + z + z * z + F::one()
+    } else {
+        F::zero()
+    }
+}
+
+/// PolyBLEP saw oscillator. A fast bandlimited algorithm for a saw wave.
+/// - Input 0: frequency (Hz).
+/// - Output 0: saw waveform in -1...1.
+#[derive(Default, Clone)]
+pub struct PolySaw<F: Float> {
+    phase: F,
+    sample_duration: F,
+    hash: u64,
+    initial_phase: Option<F>,
+}
+
+impl<F: Float> PolySaw<F> {
+    /// Create oscillator.
+    pub fn new() -> Self {
+        let mut osc = Self::default();
+        osc.reset();
+        osc.set_sample_rate(DEFAULT_SR);
+        osc
+    }
+    /// Create oscillator with initial phase in 0...1.
+    pub fn with_phase(initial_phase: f32) -> Self {
+        let mut osc = Self {
+            phase: F::zero(),
+            sample_duration: F::zero(),
+            hash: 0,
+            initial_phase: Some(F::from_f32(initial_phase)),
+        };
+        osc.reset();
+        osc.set_sample_rate(DEFAULT_SR);
+        osc
+    }
+}
+
+impl<F: Float> AudioNode for PolySaw<F> {
+    const ID: u64 = 95;
+    type Inputs = typenum::U1;
+    type Outputs = typenum::U1;
+
+    fn reset(&mut self) {
+        self.phase = match self.initial_phase {
+            Some(phase) => phase,
+            None => convert(rnd1(self.hash)),
+        };
+    }
+
+    fn set_sample_rate(&mut self, sample_rate: f64) {
+        self.sample_duration = convert(1.0 / sample_rate);
+    }
+
+    #[inline]
+    fn tick(&mut self, input: &Frame<f32, Self::Inputs>) -> Frame<f32, Self::Outputs> {
+        let phase = self.phase;
+        let delta = F::from_f32(input[0]) * self.sample_duration;
+        self.phase += delta;
+        self.phase -= self.phase.floor();
+        let value = F::new(2) * phase - F::one() - polyblep(phase, delta);
+        [value.to_f32()].into()
+    }
+
+    fn set_hash(&mut self, hash: u64) {
+        self.hash = hash;
+        self.reset();
+    }
+
+    fn route(&mut self, input: &SignalFrame, _frequency: f64) -> SignalFrame {
+        super::signal::Routing::Arbitrary(0.0).route(input, self.outputs())
+    }
+}
+
+/// PolyBLEP square oscillator. A fast bandlimited algorithm for a square wave.
+/// - Input 0: frequency (Hz).
+/// - Output 0: saw waveform in -1...1.
+#[derive(Default, Clone)]
+pub struct PolySquare<F: Float> {
+    phase: F,
+    sample_duration: F,
+    hash: u64,
+    initial_phase: Option<F>,
+}
+
+impl<F: Float> PolySquare<F> {
+    /// Create oscillator.
+    pub fn new() -> Self {
+        let mut osc = Self::default();
+        osc.reset();
+        osc.set_sample_rate(DEFAULT_SR);
+        osc
+    }
+    /// Create oscillator with initial phase in 0...1.
+    pub fn with_phase(initial_phase: f32) -> Self {
+        let mut osc = Self {
+            phase: F::zero(),
+            sample_duration: F::zero(),
+            hash: 0,
+            initial_phase: Some(F::from_f32(initial_phase)),
+        };
+        osc.reset();
+        osc.set_sample_rate(DEFAULT_SR);
+        osc
+    }
+}
+
+impl<F: Float> AudioNode for PolySquare<F> {
+    const ID: u64 = 96;
+    type Inputs = typenum::U1;
+    type Outputs = typenum::U1;
+
+    fn reset(&mut self) {
+        self.phase = match self.initial_phase {
+            Some(phase) => phase,
+            None => convert(rnd1(self.hash)),
+        };
+    }
+
+    fn set_sample_rate(&mut self, sample_rate: f64) {
+        self.sample_duration = convert(1.0 / sample_rate);
+    }
+
+    #[inline]
+    fn tick(&mut self, input: &Frame<f32, Self::Inputs>) -> Frame<f32, Self::Outputs> {
+        let phase = self.phase;
+        let delta = F::from_f32(input[0]) * self.sample_duration;
+        self.phase += delta;
+        self.phase -= self.phase.floor();
+        let square = if phase < F::from_f32(0.5) {
+            F::one()
+        } else {
+            -F::one()
+        };
+        let half = phase + F::from_f32(0.5);
+        let value = square + polyblep(phase, delta) - polyblep(half - half.floor(), delta);
+        [value.to_f32()].into()
+    }
+
+    fn set_hash(&mut self, hash: u64) {
+        self.hash = hash;
+        self.reset();
+    }
+
+    fn route(&mut self, input: &SignalFrame, _frequency: f64) -> SignalFrame {
+        super::signal::Routing::Arbitrary(0.0).route(input, self.outputs())
+    }
+}
diff --git a/src/prelude.rs b/src/prelude.rs
index 47d0fdb..300d537 100644
--- a/src/prelude.rs
+++ b/src/prelude.rs
@@ -3103,3 +3103,29 @@ pub fn fresonator_hz<F: Real, S: Shape>(
     filter.set_center_q(center, q);
     An(filter)
 }
+
+/// PolyBLEP saw wave oscillator. A fast bandlimited saw wave algorithm.
+/// - Input 0: frequency (Hz)
+/// - Output 0: saw wave
+pub fn poly_saw<F: Float>() -> An<PolySaw<F>> {
+    An(PolySaw::new())
+}
+
+/// PolyBLEP saw wave oscillator at `f` Hz. A fast bandlimited saw wave algorithm.
+/// - Output 0: saw wave
+pub fn poly_saw_hz<F: Float>(f: f32) -> An<Pipe<Constant<U1>, PolySaw<F>>> {
+    dc(f) >> poly_saw()
+}
+
+/// PolyBLEP square wave oscillator. A fast bandlimited square wave algorithm.
+/// - Input 0: frequency (Hz)
+/// - Output 0: square wave
+pub fn poly_square<F: Float>() -> An<PolySquare<F>> {
+    An(PolySquare::new())
+}
+
+/// PolyBLEP square wave oscillator at `f` Hz. A fast bandlimited square wave algorithm.
+/// - Output 0: square wave
+pub fn poly_square_hz<F: Float>(f: f32) -> An<Pipe<Constant<U1>, PolySquare<F>>> {
+    dc(f) >> poly_square()
+}
diff --git a/tests/test_basic.rs b/tests/test_basic.rs
index 67128e1..8a11b60 100644
--- a/tests/test_basic.rs
+++ b/tests/test_basic.rs
@@ -296,6 +296,7 @@ fn test_basic() {
 
     check_wave((noise() | envelope(|t| spline_noise(1, t * 10.0))) >> panner());
     check_wave(impulse::<U2>());
+    check_wave(poly_saw_hz(440.0) | poly_square_hz(4400.0));
 
     let dc42 = Net::wrap(Box::new(dc(42.)));
     let dcs = dc42.clone() | dc42;