diff --git a/packages/core/pattern.mjs b/packages/core/pattern.mjs
index b63a702f8..2c1dcfce9 100644
--- a/packages/core/pattern.mjs
+++ b/packages/core/pattern.mjs
@@ -1056,7 +1056,55 @@ function _composeOp(a, b, func) {
 
 // pattern composers
 const COMPOSERS = {
+  /**
+   * When called on a pattern `a`, with a input pattern `b` (`a.set(b)`),
+   * combines `a` and `b` such that anything defined in `b`
+   * and anything defined in `a` that is *not* defined in `b`
+   * will be in the resulting pattern.
+   *
+   * The structure is maintained from `a`,
+   * because the default pattern alignment is `in`,
+   * see the section on `Pattern Alignment`
+   * in the technical manual in the docs
+   *
+   * This is the inverse of `keep`
+   *
+   * See examples below
+   * @name set
+   * @param {Pattern} pat
+   * @returns {Pattern}
+   * @memberof Pattern
+   * @tags internal, combiners
+   * @example
+   * // because input pattern has `s` set,
+   * // it overrides the "sine" declared earlier
+   * note("c a f e").s("sine").set(s("triangle"))
+   */
   set: [(a, b) => b],
+  /**
+   * When called on a pattern `a`, with a input pattern `b` (`a.keep(b)`),
+   * combines `a` and `b` such that anything defined in `a`,
+   * and anything defined in `b` that is *not* defined in `a`
+   * will be in the resulting pattern
+   *
+   * The structure is maintained from `a`,
+   * because the default pattern alignment is `in`,
+   * see the section on `Pattern Alignment`
+   * in the technical manual in the docs
+   *
+   * This is the inverse of `set`
+   *
+   * See examples below
+   * @name keep
+   * @param {Pattern} pat
+   * @memberof Pattern
+   * @returns {Pattern}
+   * @tags internal, combiners
+   * @example
+   * // notes, already defined, will stay "c a f e",
+   * // while "s", not defined, will be set to "piano"
+   * note("c a f e").keep(note("e f a c").s("piano"))
+   */
   keep: [(a) => a],
   keepif: [(a, b) => (b ? a : undefined)],
 
diff --git a/test/__snapshots__/examples.test.mjs.snap b/test/__snapshots__/examples.test.mjs.snap
index 831e48767..5d19a0bb0 100644
--- a/test/__snapshots__/examples.test.mjs.snap
+++ b/test/__snapshots__/examples.test.mjs.snap
@@ -3012,15 +3012,6 @@ exports[`runs examples > example "delayfeedback" example index 0 1`] = `
 ]
 `;
 
-exports[`runs examples > example "delayfeedback" example index 0 2`] = `
-[
-  "[ 0/1 → 1/1 | s:bd delay:0.25 delayfeedback:0.25 ]",
-  "[ 1/1 → 2/1 | s:bd delay:0.25 delayfeedback:0.5 ]",
-  "[ 2/1 → 3/1 | s:bd delay:0.25 delayfeedback:0.75 ]",
-  "[ 3/1 → 4/1 | s:bd delay:0.25 delayfeedback:1 ]",
-]
-`;
-
 exports[`runs examples > example "delayspeed" example index 0 1`] = `
 [
   "[ 0/1 → 1/8 | note:d s:sawtooth delay:0.8 delaytime:0.5 delayspeed:2 ]",
@@ -6403,6 +6394,27 @@ exports[`runs examples > example "juxBy" example index 0 1`] = `
 ]
 `;
 
+exports[`runs examples > example "keep" example index 0 1`] = `
+[
+  "[ 0/1 → 1/4 | note:c s:piano ]",
+  "[ 1/4 → 1/2 | note:a s:piano ]",
+  "[ 1/2 → 3/4 | note:f s:piano ]",
+  "[ 3/4 → 1/1 | note:e s:piano ]",
+  "[ 1/1 → 5/4 | note:c s:piano ]",
+  "[ 5/4 → 3/2 | note:a s:piano ]",
+  "[ 3/2 → 7/4 | note:f s:piano ]",
+  "[ 7/4 → 2/1 | note:e s:piano ]",
+  "[ 2/1 → 9/4 | note:c s:piano ]",
+  "[ 9/4 → 5/2 | note:a s:piano ]",
+  "[ 5/2 → 11/4 | note:f s:piano ]",
+  "[ 11/4 → 3/1 | note:e s:piano ]",
+  "[ 3/1 → 13/4 | note:c s:piano ]",
+  "[ 13/4 → 7/2 | note:a s:piano ]",
+  "[ 7/2 → 15/4 | note:f s:piano ]",
+  "[ 15/4 → 4/1 | note:e s:piano ]",
+]
+`;
+
 exports[`runs examples > example "keyDown" example index 0 1`] = `[]`;
 
 exports[`runs examples > example "lastOf" example index 0 1`] = `
@@ -11110,6 +11122,27 @@ exports[`runs examples > example "seqPLoop" example index 0 1`] = `
 ]
 `;
 
+exports[`runs examples > example "set" example index 0 1`] = `
+[
+  "[ 0/1 → 1/4 | note:c s:triangle ]",
+  "[ 1/4 → 1/2 | note:a s:triangle ]",
+  "[ 1/2 → 3/4 | note:f s:triangle ]",
+  "[ 3/4 → 1/1 | note:e s:triangle ]",
+  "[ 1/1 → 5/4 | note:c s:triangle ]",
+  "[ 5/4 → 3/2 | note:a s:triangle ]",
+  "[ 3/2 → 7/4 | note:f s:triangle ]",
+  "[ 7/4 → 2/1 | note:e s:triangle ]",
+  "[ 2/1 → 9/4 | note:c s:triangle ]",
+  "[ 9/4 → 5/2 | note:a s:triangle ]",
+  "[ 5/2 → 11/4 | note:f s:triangle ]",
+  "[ 11/4 → 3/1 | note:e s:triangle ]",
+  "[ 3/1 → 13/4 | note:c s:triangle ]",
+  "[ 13/4 → 7/2 | note:a s:triangle ]",
+  "[ 7/2 → 15/4 | note:f s:triangle ]",
+  "[ 15/4 → 4/1 | note:e s:triangle ]",
+]
+`;
+
 exports[`runs examples > example "setDefaultJoin" example index 0 1`] = `
 [
   "[ 0/1 → 1/4 | s:saw velocity:1 note:F delay:0 ]",
diff --git a/website/src/pages/technical-manual/alignment.mdx b/website/src/pages/technical-manual/alignment.mdx
index dd3a6db5f..c2a70f1a9 100644
--- a/website/src/pages/technical-manual/alignment.mdx
+++ b/website/src/pages/technical-manual/alignment.mdx
@@ -1,11 +1,11 @@
 ---
-title: Pattern Aligment
+title: Pattern Alignment
 layout: ../../layouts/MainLayout.astro
 ---
 
 import { MiniRepl } from '../../docs/MiniRepl';
 
-# Pattern Aligment & Combination
+# Pattern Alignment & Combination
 
 One core aspect of Strudel, inherited from Tidal, is the flexible way that patterns can be combined, irrespective of their structure. Its declarative approach means a live coder does not have to think about the details of _how_ this is done, only _what_ is to be done.