From d296646d4f96da9efde6ed0c1bf1c3a29c0f27ac Mon Sep 17 00:00:00 2001
From: garrettmills <shout@garrettmills.dev>
Date: Tue, 3 Mar 2026 09:15:21 -0600
Subject: [PATCH] Add zip command

---
 src/vm/commands/index.ts |  2 ++
 src/vm/commands/zip.ts   | 38 ++++++++++++++++++++++++++++++++++++++
 src/vm/vm.ts             |  4 ++++
 3 files changed, 44 insertions(+)
 create mode 100644 src/vm/commands/zip.ts

diff --git a/src/vm/commands/index.ts b/src/vm/commands/index.ts
index 8cdfea7..70ce909 100644
--- a/src/vm/commands/index.ts
+++ b/src/vm/commands/index.ts
@@ -45,6 +45,7 @@ import {Drop} from "./drop.js";
 import {Sort} from "./sort.js";
 import {Set} from "./set.js";
 import {Assign} from "./assign.js";
+import {Zip} from "./zip.js";
 
 export type Commands = Command<CommandData>[]
 export const commands: Commands = [
@@ -94,4 +95,5 @@ export const commands: Commands = [
     new Upper,
     new Word,
     new Words,
+    new Zip,
 ]
diff --git a/src/vm/commands/zip.ts b/src/vm/commands/zip.ts
new file mode 100644
index 0000000..4e66848
--- /dev/null
+++ b/src/vm/commands/zip.ts
@@ -0,0 +1,38 @@
+import {Command, ParseContext, StrDestructured, StrTerm} from "./command.js";
+import {Awaitable} from "../../util/types.js";
+import {LexInput} from "../lexer.js";
+import {StrVM} from "../vm.js";
+
+export type ZipData = {
+	with: StrTerm,
+}
+
+export class Zip extends Command<ZipData> {
+	attemptParse(context: ParseContext): Awaitable<ZipData> {
+		return {
+			with: context.popTerm(),
+		}
+	}
+
+	getDisplayName(): string {
+		return 'zip'
+	}
+
+	isParseCandidate(token: LexInput): boolean {
+		return this.isKeyword(token, 'zip')
+	}
+
+	execute(vm: StrVM, data: ZipData): Awaitable<StrVM> {
+		return vm.replaceContextMatchingTerm(ctx => ({
+			destructured: lhs => {
+				const rhs = ctx.resolveDestructured(data.with)
+				const zipped: StrDestructured['value'] = []
+				for ( let i = 0; i < Math.max(lhs.length, rhs.length); i += 1 ) {
+					if ( lhs[i] ) zipped.push(lhs[i])
+					if ( rhs[i] ) zipped.push(rhs[i])
+				}
+				return zipped
+			},
+		}))
+	}
+}
diff --git a/src/vm/vm.ts b/src/vm/vm.ts
index 07b0c2e..2540c72 100644
--- a/src/vm/vm.ts
+++ b/src/vm/vm.ts
@@ -266,6 +266,10 @@ export class ExecutionContext {
         return unwrapString(this.resolveRequired(term))
     }
 
+    resolveDestructured(term: StrTerm) {
+        return unwrapDestructured(this.resolveRequired(term))
+    }
+
     resolveInt(term: StrTerm): number {
         return unwrapInt(this.resolveRequired(term))
     }