Builder's Notebook

Hey. I'm Josh, and I build things.

Notes on compilers, WebAssembly, testing infrastructure, and the awkward systems problems that show up when tools start getting real.

WebAssembly Developer Tools Testing Systems

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Tooling, validation, and practical systems work

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WASM

Introducing sfo-mb: a beginner-friendly guide to a MoonBit type checker

A beginner-friendly look at sfo-mb, showing the big ideas behind a type checker, how System F-ω ideas fit together, and simple usage patterns to get started.

Joshua Tenner Apr 4, 2026

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WASM

Introducing as-harness, a new testing framework for AssemblyScript

A first look at as-harness, a WASM-first AssemblyScript test framework with deterministic planning, coverage, snapshots, and multiple runtime hosts.

Joshua Tenner Mar 24, 2026

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Hey. I'm Josh, and I build things.

Latest Thinking

Introducing sfo-mb: a beginner-friendly guide to a MoonBit type checker

Introducing as-harness, a new testing framework for AssemblyScript

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