--- title: Wasm is not quite a stack machine | daily.dev description: WebAssembly is widely described as a stack machine, but a closer look at its instruction set reveals it lacks the stack manipulation operations (dup, swap,... canonical: https://daily.dev/posts/wasm-is-not-quite-a-stack-machine-yyk0doskb twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Wasm is not quite a stack machine | daily.dev og:description: WebAssembly is widely described as a stack machine, but a closer look at its instruction set reveals it lacks the stack manipulation operations (dup, swap,... og:url: https://daily.dev/posts/wasm-is-not-quite-a-stack-machine-yyk0doskb og:image: https://api.daily.dev/og/posts/yYK0Doskb.png og:image:alt: Wasm is not quite a stack machine og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Wasm is not quite a stack machine **[Lobsters](https://daily.dev/sources/lobsters)** · 6 min read · 0 upvotes · 0 comments ## Summary WebAssembly is widely described as a stack machine, but a closer look at its instruction set reveals it lacks the stack manipulation operations (dup, swap, over, rot) that define real stack machines like the JVM. Without these, Wasm cannot reuse values or perform common subexpression elimination without introducing local variables. This makes Wasm behave more like a register machine with compound expressions encoded in Reverse Polish notation — the stack is just an encoding detail, not a fundamental design. The multi-value extension further confirms this: before it, control flow blocks couldn't interact with the stack at all. The practical takeaway is that experience with traditional stack-based VMs doesn't transfer cleanly to Wasm. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Thoughts on WebAssembly as a stack machine](https://daily.dev/posts/thoughts-on-webassembly-as-a-stack-machine-nidfun9ol) · Eli Bendersky · 2 upvotes · 0 comments - [WebAssembly is everywhere. 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