CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Commands

# Run tests (short mode, shuffled)
make test

# Run tests with race detector and coverage
make test-acc

# View coverage report (after test-acc)
make test-coverage

# Lint
make lint

# Run a single test
go test -run TestName ./slice/
go test -run TestName ./maps/

Architecture

This is a Go generics library providing functional programming primitives. It requires Go 1.24+.

Two packages:

slice/ — operations on slices:

• Map[T, R] / MapToPtr[T] — transform elements
• Filter[T] — select elements by predicate (MatchFn[T])
• FoldL[T, A] / FoldR[T, A] — reduce from left/right
• Take[T] — take first N elements
• Group[T] — group elements by key
• Frequencies[T] — count occurrences
• matchers.go defines shared MatchFn[T] type

maps/ — operations on maps:

• ToMap[K, T] — convert slice to map via key function (errors on duplicates)
• ToSlice[K, T] — convert map values to slice
• Keys[K, T] — extract map keys as slice

Each function is generic and uses type constraints (any, comparable). Tests use github.com/google/go-cmp/cmp for comparisons.