nushell-pro

SKILL.md

Nushell Pro — Best Practices & Security Skill

Write idiomatic, performant, secure, and maintainable Nushell scripts. This skill enforces Nushell conventions, catches security issues, and helps avoid common pitfalls.

Core Principles

Think in pipelines — Data flows through pipelines; prefer functional transformations over imperative loops

Immutability first — Use let by default; only use mut when functional alternatives don't apply

Structured data — Nushell works with tables, records, and lists natively; leverage structured data over string parsing

Static parsing — All code is parsed before execution; source/use require parse-time constants

Implicit return — The last expression's value is the return value; no need for echo or return

Scoped environment — Environment changes are local to their block; use def --env when caller-side changes are needed

Type safety — Annotate parameter types and input/output signatures for better error detection and documentation

Parallel ready — Immutable code enables easy par-each parallelization

Critical: Pipeline Input vs Parameters

Pipeline input ($in) is NOT interchangeable with function parameters!