This presentation was recorded at GOTO Copenhagen 2025. #GOTOcon #GOTOcph
https://gotocph.com

José Valim - Creator of Elixir & Co-Author of "Adopting Elixir: From Concept to Production"

RESOURCES
https://bsky.app/profile/josevalim.bsky.social
https://twitter.com/josevalim
https://github.com/josevalim
https://www.linkedin.com/in/josevalim
https://dashbit.co

Links
https://tidewave.ai
https://agents.md
https://simonwillison.net/2025/Jun/16/the-lethal-trifecta
https://xkcd.com/327

ABSTRACT
As AI agents become increasingly integrated into software development, we find ourselves facing questions about how our programming languages and tools should evolve, in order to make coding agents and ourselves more productive.

This talk breaks down coding agents into distinct axes (instructions, tools, and runtimes) and discusses practical solutions (AGENTS.md, runtime introspection, etc) to improve both developer and agentic experiences, whether you're using AI tools daily or building developer tooling. [...]

TIMECODES
00:00 Intro
01:59 Improving coding agents
02:53 Improving agents: Instructions
08:54 Improving agents: Tools
18:15 Improving agents: Runtime
18:42 Demo
24:17 Improving agents: Runtime continued
31:31 Building integrated runtimes
36:37 Summary
37:07 Outro

Download slides and read the full abstract here:
https://gotocph.com/2025/sessions/3740

RECOMMENDED BOOKS
Jose Valim, Chris McCord & Bruce Tate • Programming Phoenix 1.4 • https://amzn.to/3MIml6r
Jose Valim Ben Marx & Bruce Tate • Adopting Elixir • https://amzn.to/4pczr9o
Jose Valim • Crafting Rails 4 Applications • https://amzn.to/493BWVp
Saša Jurić • Elixir in Action • https://amzn.to/2RZh5eN
Dave Thomas • Programming Elixir ≥ 1.6: Functional • https://amzn.to/34Dw3O5

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GOTO's resource offers insights, tutorials, and resources for software developers, architects, and technology leaders. Readers can learn about emerging technologies, industry trends, and best practices for software development. With articles, talks, and workshops, GOTO provides  guidance and expertise for staying ahead in the ever-evolving world of technology.

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José Valim (creator of Elixir, CEO of Tidewave.ai) presents a practical framework for improving coding agents across three dimensions: instructions, tools, and runtimes. Key ideas include using agents.md files to encode project-specific rules and common pitfalls, the limitations of MCP (pull-only model, redundancy with existing code capabilities, and prompt injection security risks via the 'little trifecta'), and the case for building integrated custom runtimes instead of relying on fragmented MCP tooling. He demos Tidewave, a browser-based coding agent runtime for Phoenix/Rails that maps DOM elements to source templates, runs contextual browser tests, and queries the database to verify feature correctness. The talk concludes that introspection (compiler, runtime, and domain-specific), unified documentation repositories, and sandboxing are the key building blocks for next-generation agentic developer tools.

Coding Agents & Language Evolution: Navigating Uncharted Waters • José Valim • GOTO 2025