autojanet/skills/understand/languages/go.md

Go Language Prompt Snippet

Key Concepts

• Goroutines: Lightweight concurrent functions launched with go keyword
• Channels: Typed conduits for communication and synchronization between goroutines
• Interfaces: Implicitly satisfied contracts — no implements keyword needed
• Struct Embedding: Composition mechanism providing field and method promotion
• Error Handling: Explicit error return values (error interface) instead of exceptions
• Defer/Panic/Recover: Deferred cleanup, unrecoverable errors, and recovery mechanism
• Slices vs Arrays: Arrays are fixed-size values; slices are dynamic views backed by arrays
• Pointers: Explicit pointer types for pass-by-reference semantics (no pointer arithmetic)
• Context Propagation: context.Context carries deadlines, cancellation, and request-scoped values
• Init Functions: Package-level init() runs automatically before main() for setup

Import Patterns

• import "package" — single package import
• import alias "package" — aliased import to avoid name conflicts
• import ( ... ) — grouped import block (standard library, then external, then internal)
• import _ "package" — blank import for side effects only (e.g., driver registration)

File Patterns

• *_test.go — test files in the same package (or _test package for black-box tests)
• cmd/ — directory containing main packages (binary entry points)
• internal/ — packages only importable by parent module (enforced by compiler)
• pkg/ — public library packages (convention, not enforced)
• go.mod — module definition with dependency versions
• go.sum — cryptographic checksums for dependencies

Common Frameworks

• Gin — High-performance HTTP framework with middleware support
• Echo — Minimalist web framework with built-in middleware
• Fiber — Express-inspired framework built on fasthttp
• Chi — Lightweight, composable HTTP router
• GORM — ORM library with associations, hooks, and migrations

Example Language Notes

Implements io.Reader interface implicitly — no explicit declaration needed, just matching method signatures. This enables any type with a Read([]byte) (int, error) method to be used wherever io.Reader is expected.

The internal/ directory enforces encapsulation at the compiler level, preventing external packages from importing implementation details — stronger than naming convention.