What Elixir Gives a Coding Harness for Free
José Valim's case for Elixir as a coding-agent harness holds up on the runtime. The tax is the ecosystem around it: sandboxing, plugins, and SDKs.
Writing · Tag
Posts tagged Elixir
34 posts on Elixir, page 2 of 3. Or browse the full writing index →
Posts tagged Elixir
Metering LLM Usage Per Customer in Phoenix
ReqLLM emits token-usage telemetry; turning it into a per-customer invoice line needs an append-only ledger, integer-cent math, and idempotent writes.
Phoenix Secrets: runtime.exs, Fly.io, and LLM Keys
The compile-time trap in config.exs, why System.fetch_env! should crash your boot, and how to actually wire Fly secrets and LLM keys through a Phoenix release.
Multi-Tenant AI SaaS in Phoenix: Isolation That Holds
Tenant isolation for AI SaaS in Phoenix: per-tenant API key tradeoffs, Ecto context scoping, and the pgvector bug that leaks one tenant into another.
Instrumenting LLM Calls in Phoenix with Telemetry
ReqLLM already emits token cost and latency telemetry events. The real gap is a few lines wiring them into LiveDashboard and PromEx, not another SaaS bill.
10 Ecto Query Patterns for N+1 and Beyond
The Iron Law for has_many vs belongs_to, plus when Dataloader, subqueries, or raw SQL are the honest fix, not another preload tutorial.
Isolating Parallel Claude Code Agents in Phoenix
Elixir/Phoenix mechanics for parallel Claude Code agents: templating PORT per worktree, one Postgres DB per branch, and asset-watcher collisions nobody covers.
What Together AI's $800M Round Says About Elixir
Together AI raised $800M at an $8.3B valuation. A since-removed job posting showed Elixir/Phoenix on the BEAM running its auth and access control.
Why We'd Pick Elixir for an AI Startup Backend
A founder-readable case for Elixir as an AI startup's backend: what the BEAM gets right for agents, streaming, and durable jobs, and when to skip it.
12 Phoenix LiveView Patterns for Production
Twelve Phoenix LiveView patterns that hold up in production: streams vs assigns, async mounts, PubSub gating, and the failure mode behind each one.
Testing AI Agent Outputs in Elixir with ExUnit
An ExUnit suite for agent loops in Elixir that asserts on tool-call order and hallucinations as well as final strings, plus evals that survive model upgrades.
TDD With Claude Code in Elixir: What Holds Up
Where TDD with Claude Code actually holds up in an Elixir/Phoenix codebase (ExUnit async, mix precommit, Ecto.Multi idempotency) and where it breaks.