Golang Samber LoSAFE

🧑🎨 A collection of Golang agentic skills that works

The instruction file, verbatim from the audited commit — this is the text the model reads, and the surface the audit's instruction layer examines. Quoted here so you can judge it without cloning anything.

---
name: golang-samber-lo
description: "Functional programming helpers for Golang using samber/lo — 500+ type-safe generic functions for slices, maps, channels, strings, math, tuples, and concurrency (Map, Filter, Reduce, GroupBy, Chunk, Flatten, Find, Uniq, etc.). Core immutable package (lo), concurrent variants (lo/parallel aka lop), in-place mutations (lo/mutable aka lom), lazy iterators (lo/it aka loi for Go 1.23+), and experimental SIMD (lo/exp/simd). Apply when using or adopting samber/lo, when the codebase imports github.com/samber/lo, or when implementing functional-style data transformations in Go. Not for streaming pipelines (→ See `samber/cc-skills-golang@golang-samber-ro` skill)."
user-invocable: true
license: MIT
compatibility: Designed for Claude Code, Codex or similar harness, and for projects using Golang.
metadata:
  author: samber
  version: "1.2.2"
  openclaw:
    emoji: "🧰"
    homepage: https://github.com/samber/cc-skills-golang
    requires:
      bins:
        - go
    install: []
    skill-library-version: "1.53.0"
allowed-tools: Read Edit Write Glob Grep Bash(go:*) Bash(golangci-lint:*) Bash(git:*) mcp__context7__resolve-library-id mcp__context7__query-docs AskUserQuestion Bash(godig:*) Bash(gopls:*) LSP mcp__gopls__*
paths:
  - "**/*.go"
---

**Persona:** You are a Go engineer who prefers declarative collection transforms over manual loops. You reach for `lo` to eliminate boilerplate, but you know when the stdlib is enough and when to upgrade to `lop`, `lom`, or `loi`.

# samber/lo — Functional Utilities for Go

Lodash-inspired, generics-first utility library with 500+ type-safe helpers for slices, maps, strings, math, channels, tuples, and concurrency. Zero external dependencies. Immutable by default.

**Official Resources:**

- [github.com/samber/lo](https://github.com/samber/lo)
- [lo.samber.dev](https://lo.samber.dev)
- [pkg.go.dev/github.com/samber/lo](https://pkg.go.dev/github.com/samber/lo)

This skill is not exhaustive — refer to library documentation and code examples for more information:

- For Go package docs, symbols, versions, importers, and known vulnerabilities, → See `samber/cc-skills-golang@golang-pkg-go-dev` skill (`godig`), preferred over Context7 for Go package facts.
- To navigate this library's usage in your own code (definitions, call sites, diagnostics), → See `samber/cc-skills-golang@golang-gopls` skill (`gopls`).
- Context7 remains a fallback for docs not indexed on pkg.go.dev.

## Why samber/lo

Go's stdlib `slices` and `maps` packages cover ~10 basic helpers (sort, contains, keys). Everything else — Map, Filter, Reduce, GroupBy, Chunk, Flatten, Zip — requires manual for-loops. `lo` fills this gap:

- **Type-safe generics** — no `interface{}` casts, no reflection, compile-time checking, no interface boxing overhead
- **Immutable by default** — returns new collections, safe for concurrent reads, easier to reason about
- **Composable** — functions take and return slices/maps, so they chain without wrapper types
- **Zero dependencies** — only Go stdlib, no transitive dependency risk
- **Progressive complexity** — start with `lo`, upgrade to `lop`/`lom`/`loi` only when profiling demands it
- **Error variants** — most functions have `Err` suffixes (`MapErr`, `FilterErr`, `ReduceErr`) that stop on first error

## Installation

```bash
go get github.com/samber/lo
```

| Package | Import | Alias | Go version |
| --- | --- | --- | --- |
| Core (immutable) | `github.com/samber/lo` | `lo` | 1.18+ |
| Parallel | `github.com/samber/lo/parallel` | `lop` | 1.18+ |
| Mutable | `github.com/samber/lo/mutable` | `lom` | 1.18+ |
| Iterator | `github.com/samber/lo/it` | `loi` | 1.23+ |
| SIMD (experimental) | `github.com/samber/lo/exp/simd` | — | 1.25+ (amd64 only) |

## Choose the Right Package

Start with `lo`. Move to other packages only when profiling shows a bottleneck or when lazy evaluation is explicitly needed.

| Package | Use when | Trade-off |
| --- | --- | --- |
| `lo` | Default for all transforms | Allocates new collections (safe, predictable) |
| `lop` | CPU-bound work on large datasets (1000+ items) | Goroutine overhead; not for I/O or small slices |
| `lom` | Hot path confirmed by `pprof -alloc_objects` | Mutates input — caller must understand side effects |
| `loi` | Large datasets with chained transforms (Go 1.23+) | Lazy evaluation saves memory but adds iterator complexity |
| `simd` | Numeric bulk ops after benchmarking (experimental) | Unstable API, may break between versions |

**Key rules:**

- `lop` is for CPU parallelism, not I/O concurrency — for I/O fan-out, use `errgroup` instead
- `lom` breaks immutability — only use when allocation pressure is measured, never assumed
- `loi` eliminates intermediate allocations in chains like `Map → Filter → Take` by evaluating lazily
- For reactive/streaming pipelines over infinite event streams, → see `samber/cc-skills-golang@golang-samber-ro` skill + `samber/ro` package

For detailed package comparison and decision flowchart, see [Package Guide](./references/package-guide.md).

## Core Patterns

### Transform a slice

```go
// ✓ lo — declarative, type-safe
names := lo.Map(users, func(u User, _ int) string {
    return u.Name
})

// ✗ Manual — boilerplate, error-prone
names := make([]string, 0, len(users))
for _, u := range users {
    names = append(names, u.Name)
}
```

### Filter + Reduce

```go
total := lo.Reduce(
    lo.Filter(orders, func(o Order, _ int) bool {
        return o.Status == "paid"
    }),
    func(sum float64, o Order, _ int) float64 {
        return sum + o.Amount
    },
    0,
)
```

### GroupBy

```go
byStatus := lo.GroupBy(tasks, func(t Task, _ int) string {
    return t.Status
})
// map[string][]Task{"open": [...], "closed": [...]}
```

### Error variant — stop on first error

```go
results, err := lo.MapErr(urls, func(url string, _ int) (Response, error) {
    return http.Get(url)
})
```

## Common Mistakes

| Mistake | Why it fails | Fix |
| --- | --- | --- |
| Us

SAFEgrade B · trust 89/100 Nothing in the source contradicts what it says it does. Grade A is reserved for packages that have also passed the behavioural sandbox.

What the source does

Filesystem

none-observed

Network

none-observed

Shell

none-observed

Dependencies

pinned

Secrets in source

none-found

Findings (0)

No findings outside the package's declared scope.

Gates applied: no_behavioural_pass.