lean-ja / lean-ja/lean-by-example
pure と return が異なる例
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コード例
- Dominant language
- Lean
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- 188
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- Avg merge
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- Merged PRs (30d)
- 6
Description
def main (args : List String) : IO UInt32 := do
match configFromArgs args with
| some config =>
let targetDir ←
if config.startDir == "" then IO.currentDir
else pure config.startDir
(dirTree targetDir).run config
pure 0
| none =>
IO.eprintln s!"Didn't understand argument(s) {args}\n"
IO.eprintln usage
pure 1
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
The issue only provides the main example containing configFromArgs, IO.currentDir, and dirTree. Start by locating that example and comparing the roles of pure and return in the shown code; done means the example or its surrounding explanation clearly resolves the reported difference.
Written by the indexing model from the issue text.
Assessment
- Domain
- documentation
- Issue type
- Documentation
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 30/100