golang-samber-mo Skill for Claude: What It Does and How to Install It

Makes Claude use samber/mo in Go: Option, Result and Either types for nil-safe values and composable error handling.

Installs: 39K; on skills.sh
Stars: 3.7K; on GitHub
Files: 7; besides SKILL.md
Updated: Nov 2026; last repo commit

This skill covers samber/mo, a Go library of monadic types. Claude picks between Option for values that may be absent, Result for success or failure and Either for two valid alternatives.

It also explains a Go limit: direct methods cannot change the type, so type-changing steps use the sub-package functions or mo.Do. It asks Claude to reason carefully about pipeline design and mentions ultrathink on Claude Code.

Good for

Go developers who like functional patterns from Rust or Scala
Teams removing nil checks with Option types
Anyone chaining steps that can fail with Result pipelines

Install golang-samber-mo

Claude Code

Copy this prompt.

Install the golang-samber-mo skill in Claude Code. Run this command:

npx skills add https://github.com/samber/cc-skills-golang --skill golang-samber-mo

Then check that it loaded and tell me how to use it.

2
Paste it into Claude Code. It shows the change and asks before running it.

Requires Node.js.

From its listing on skills.sh. Source.

What's in the skill

When it loads

Monadic types for Golang using samber/mo — Option, Result, Either, Future, IO, Task, and State types for type-safe nullable values, error handling, and functional composition with pipeline sub-packages. Apply when using or adopting samber/mo, when the codebase imports `github.com/samber/mo`, or when considering functional programming patterns as a safety design for Golang. Not for nil-safety and zero-value design without this library (→ See `samber/cc-skills-golang@golang-safety` skill), nor for native error wrapping with fmt.Errorf, errors.Is and errors.As (→ See `samber/cc-skills-golang@golang-error-handling` skill).

Sections in SKILL.md

Core Types at a Glance
Option[T] — Nullable Values Without nil
Result[T] — Error Handling as Values
Either[L, R] — Discriminated Union of Two Types
Do Notation — Imperative Style with Monadic Safety
Pipeline Sub-Packages vs Direct Chaining
Common Patterns
JSON API responses with Option
Database nullable columns
Wrapping existing Go APIs
Uniform extraction with Fold
Best Practices
Cross-References

Key facts

Author: samber
License: MIT
Installs on skills.sh: 38,996 (Nov 2, 2026)
GitHub stars: 3,749 for the whole samber/cc-skills-golang repo (Nov 2, 2026)
Last repo commit: Nov 1, 2026
What it includes: 8 files including SKILL.md: 6 reference guides and an evals/evals.json file
Needs: A Go project and the go command (SKILL.md lists go as a required binary)
Skill version: 1.1.2
Library version covered: 1.16.0
Starts: Loads on its own when your Go code uses the library (its description says so). Also a slash command, since it is marked user-invocable
Works in: Claude Code, Codex or similar tools per the SKILL.md compatibility line. The README also names Gemini, Copilot, Antigravity and Cursor

What it includes

A value that is present or absent, without nil
Methods include Some, None, Get, OrElse, Map and Match. It works with JSON and database scanning.
Try: “Replace these nil pointer fields with samber/mo Option values.”
Write · Option[T]
Success or failure as a value
Ok, Err, Try, Map, FlatMap and MapErr. Direct methods cannot change the type parameter.
Write · Result[T]
One of two valid types
Use Result when one side is an error and Either when both sides are valid. Either3 to Either5 add more variants.
Write · Either[L, R]
mo.Do wraps imperative code in a Result
Catches panics from MustGet so straight-line code still gets error propagation.
Write · Do notation
option.Map, result.Map and Pipe functions
Needed when the output type differs from the input type.
Write · Pipeline sub-packages
Advanced types in references/advanced-types.md
Reference guide for the other monadic types in the library.
Read · Future, IO, Task, State
Introduction to why monads help in Go
Reference guide in references/monads-guide.md.
Read · Monads guide

From the official docs

Permissions

Low risk

The skill lets Claude edit your Go files and run go, golangci-lint and git commands, and it may fetch web pages. Keep permission prompts on for git and review diffs.

What it can do

Read your data
Create and change things
Delete things
Read-only mode

Watch out for

It lists git and shell commands as allowed tools
The allowed-tools line covers any go, golangci-lint and git command (git:*), not just read ones. Keep Claude Code's permission prompts on for git commands that change history. github.com
It may fetch web pages or query Context7
It lists WebFetch and the Context7 tools as allowed. Library names and questions can leave your machine. Do not put secrets in prompts about this code. github.com

Security advisories

No published security advisories as of Nov 2, 2026.

Technical details

Turning on read-only	No read-only mode in SKILL.md. Use version control.
Talks to	WebFetch is listed as an allowed tool. Library lookups go to Context7 if the Context7 MCP server is installed (the skill uses it as a fallback)
Sign-in and keys	SKILL.md does not mention any account or key.
Scopes	Reads and edits files in your Go project SKILL.md lists these as allowed tools: go, golangci-lint, git, godig and gopls commands

Questions

What does the golang-samber-mo skill do?

It teaches Claude to use samber/mo for monadic types in Go. Claude uses Option, Result and Either, and chains them with pipelines instead of repeated nil and error checks.

How do I install golang-samber-mo?

Use the install box at the top of this page. It is a text skill with reference guides, so there is nothing to compile. Start a new session so it loads, then work in a Go project.

When should I not use it?

Its description says it is not for nil-safety and zero-value design without this library (use the golang-safety skill), nor for native error wrapping with fmt.Errorf, errors.Is and errors.As (use golang-error-handling).

Result or Either?

Use Result when one path is an error. Use Either when both paths are valid alternatives, such as cached or fresh data.

Does it need other skills from the same repo?

SKILL.md does not list any other skill as required. SKILL.md points to related skills in samber/cc-skills-golang for side topics, and the README says installing only a subset gives a partial and possibly inconsistent view of the guidelines. For best results it recommends installing the general-purpose Go skills together.

Is golang-samber-mo safe?

Mostly, for your own Go projects. It is instructions plus reference files, and it lets Claude edit files and run go and git commands. Review diffs, keep the project under version control and avoid secrets in prompts.

Does golang-samber-mo work in Codex, Cursor or the Claude app?

It is designed for Claude Code, Codex or a similar tool, and the README says the skills are built for Claude Code, Codex, Gemini, Copilot, Antigravity and Cursor. Because it works on your Go files and uses the go command, use a coding tool rather than the Claude app.

Information

updated Nov 2, 2026

Repository: samber/cc-skills-golang
Folder: skills/golang-samber-mo

samber/cc-skills-golang skills.sh

Sources

Docs, issue trackers and discussions this page is built from.

Show all 2

golang-samber-mo SKILL.md · github.com
cc-skills-golang README · github.com