菜单
Avoid mutable variables like IORef, STRef, and ST in Haskell and prefer immutable records. Use STM variables such as TVar for thread communication. Use when writing or reviewing Haskell code that uses mutable state or concurrency.
用 Codex 或 Claude 帮你安装 复制这段 Prompt，粘贴到 Codex、Claude 或其他助手里，让它检查 Skill 页面并帮你完成安装。
Generate a commit message from staged changes and let the user review before committing. Use when the user wants to commit changes or create a git commit.
Generate a GitHub pull request title and body from the current branch and let the user review before creation. Use when the user wants to create a pull request.
Investigate any topic by querying multiple external sources (web, official docs, GitHub, MCP servers). Use whenever a question requires information not already in the working context, including library behavior, API specifications, error diagnostics, version comparisons, or general factual lookup.
himari is ncaq's rio-like custom Haskell Prelude. Import it with a single `import Himari`, never `import Himari.Prelude` or other submodules directly. Use when writing or reviewing Haskell code in a project that depends on the himari package.
Prefer the most specific built-in method over general-purpose ones in TypeScript/JavaScript. Use includes over indexOf, some over filter().length, find over filter()[0], flatMap over map().flat(), at(-1) over length-based access, startsWith/endsWith/includes over indexOf on strings, structuredClone over JSON round-trip. Use when writing or reviewing code that searches, tests, transforms arrays, objects, or strings.
Avoid for loops (C-style, for...of, for...in) in TypeScript/JavaScript. Prefer higher-order Array methods like map, filter, find, some, every, reduce. Use when writing or reviewing loops or iteration over arrays, objects, Map, Set, or String.
| name | mutable |
| description | Avoid mutable variables like IORef, STRef, and ST in Haskell and prefer immutable records. Use STM variables such as TVar for thread communication. Use when writing or reviewing Haskell code that uses mutable state or concurrency. |
| user-invocable | false |
一般的なプログラミングにおいても、 mutableな変数はできるだけ避けるべきだとされています。
特にHaskellは純粋関数型言語です。
immutableにレコードを差分更新することを効率よく行えるようになっているので、 mutableな変数が欲しいことは滅多にありません。
mutableな変数を実現する機構は原則禁止です。
例えば以下の機構は避けるべきです。
IORefSTRefSTスレッド間の通信を行いたい場合はミュータブルな変数を使った方がスムーズなことがあります。
例えば以下の型が該当します。
TVarTMVarTChanTQueueTBQueueしかしこれらも低レイヤーな機構なので、 そのまま深く入り組ませずに、 抽象化して使うべきです。