Golang Data Structures

What it does

When your agent uses it

• Optimizing Go data structures
• Slice/map internals

Example prompts

• “/golang-data-structures”

Requirements

• Compatibility (from SKILL.md): Designed for Claude Code, Codex or similar harness, and for projects using Golang.
• Pre-approved tools (allowed-tools): Read, Edit, Write, Glob, Grep, Bash(go:*), Bash(golangci-lint:*), Bash(git:*), Agent, Bash(godig:*), Bash(gopls:*), LSP, mcp__gopls__*, mcp__context7__resolve-library-id, mcp__context7__query-docs

Workflow steps

8 steps, taken from the first numbered list in SKILL.md.

1. 1Preallocate slices and maps with make(T, 0, n) / make(map[K]V, n) when size is known or estimable — avoids repeated growth copies and…
2. 2Arrays SHOULD be preferred over slices only for fixed, compile-time-known sizes (hash digests, IPv4 addresses, matrix dimensions)
3. 3NEVER rely on slice capacity growth timing — the growth algorithm changed between Go versions and may change again; your code should not…
4. 4Use container/heap for priority queues, container/list only when frequent middle insertions are needed, container/ring for fixed-size…
5. 5strings.Builder MUST be preferred for building strings; bytes.Buffer MUST be preferred for bidirectional I/O (implements both io.Reader…
6. 6Generic data structures SHOULD use the tightest constraint possible — comparable for keys, custom interfaces for ordering
7. 7unsafe.Pointer MUST only follow the 6 valid conversion patterns from the Go spec — NEVER store in a uintptr variable across statements
8. 8weak.Pointer[T] (Go 1.24+) SHOULD be used for caches and canonicalization maps to allow GC to reclaim entries

What it can do on your machine

Read from SKILL.md and the folder at commit 8876467. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Read
  • Edit
  • Write
  • Glob
  • Grep
  • Bash(go:*)
  • Bash(golangci-lint:*)
  • Bash(git:*)
  • Agent
  • Bash(godig:*)

  …and 5 more on the same allowed-tools line.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are go).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • go.dev
  • research.swtch.com

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

• Compatibility

  Designed for Claude Code, Codex or similar harness, and for projects using Golang.

  From compatibility in the SKILL.md frontmatter.

Context cost

Golang Data Structures loads about 2.6k tokens when it runs, and up to ~6.3k if it reads all its reference files. Until then it costs about 79 tokens; SKILL.md has 988 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~79

When it runs · the whole SKILL.md, loaded when a task matches

~2.6k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~6.3k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from context-labs/whip at commit 8876467, republished under its MIT licence (© context-labs). 988 words, ~2,557 tokens.

name

golang-data-structures

description

Golang data structures — slices/maps internals (capacity growth, preallocation, hash buckets), slices/maps packages, container/list/heap/ring, strings.Builder vs bytes.Buffer, generic collections, unsafe/weak pointers. Use when choosing or optimizing Go data structures or slice/map internals.

allowed-tools

Read, Edit, Write, Glob, Grep, Bash(go:*), Bash(golangci-lint:*), Bash(git:*), Agent, Bash(godig:*), Bash(gopls:*), LSP, mcp__gopls__*, mcp__context7__resolve-library-id, mcp__context7__query-docs

compatibility

Designed for Claude Code, Codex or similar harness, and for projects using Golang.

user-invocable

true

license

MIT

metadata.author

samber

metadata.version

1.2.0

paths

**/*.go

// Exact size known
users := make([]User, 0, len(ids))

// Approximate size known
results := make([]Result, 0, estimatedCount)

// Pre-grow before bulk append (Go 1.21+)
s = slices.Grow(s, additionalNeeded)

m := make(map[string]*User, len(users)) // avoids rehashing during population

type Digest [32]byte           // fixed-size, value type
var grid [3][3]int             // multi-dimensional
cache := map[[2]int]Result{}   // arrays are comparable — usable as map keys

type Set[T comparable] map[T]struct{}

func (s Set[T]) Add(v T)          { s[v] = struct{}{} }
func (s Set[T]) Contains(v T) bool { _, ok := s[v]; return ok }

© context-labs, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 6 other files (references) in .agents/skills/golang-data-structures of context-labs/whip.

• SKILL.md
• evals/evals.json
• references/containers.md
• references/generics.md
• references/map-internals.md
• references/pointers.md
• references/slice-internals.md

Open the folder on GitHubat commit 8876467

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in context-labs/whip, which our catalogue first saw on October 7, 2026.

• samber/cc-skills-golangskills/golang-data-structures