mirror of
https://github.com/rjNemo/underscore
synced 2026-06-06 02:26:42 +00:00
Ruidy
40ac16261e
BREAKING CHANGE: Drop function now correctly drops first N elements
instead of removing element at specific index.
Changes:
- Renamed old Drop behavior to RemoveAt function
- Implemented correct Drop semantics (drop first N elements)
- Added comprehensive tests for both functions
Drop (NEW behavior):
- Drop([]int{1,2,3,4,5}, 2) → [3,4,5] (drops first 2 elements)
- Returns empty slice if n >= len(values)
- Returns original slice if n <= 0
RemoveAt (OLD Drop behavior):
- RemoveAt([]int{1,2,3,4,5}, 2) → [1,2,4,5] (removes index 2)
- Returns original slice if index out of bounds
- Pre-allocates with capacity len(values)-1
Tests added:
- Drop: 5 tests (basic, none, all, empty, single)
- RemoveAt: 6 tests (basic, first, last, bounds, empty, single)
Documentation updated:
- README.md: Added RemoveAt to function list
- CLAUDE.md: Marked Drop semantics as fixed
- ACTION_PLAN.md: Updated completion status
Migration guide:
- Old: Drop(slice, index) → New: RemoveAt(slice, index)
- New Drop usage: Drop(slice, n) drops first n elements
Coverage: 98.8% (maintained)
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
213 lines
5.3 KiB
Markdown
213 lines
5.3 KiB
Markdown
# \_Underscore
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[](https://pkg.go.dev/github.com/rjNemo/underscore)
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[](https://www.bestpractices.dev/projects/9726)
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`underscore` is a `Go` library providing useful functional programming helpers without
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extending any built-in objects.
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It is mostly a port from the `underscore.js` library based on generics brought by
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`Go 1.18`.
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## Usage
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📚 Follow this link for the [documentation](https://underscore.onrender.com/).
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Install the library using
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```sh
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go get github.com/rjNemo/underscore@latest
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```
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Please check out the [examples](examples) to see how to use the library.
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```go
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package main
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import (
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"fmt"
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u "github.com/rjNemo/underscore"
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)
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func main() {
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numbers := []int{1, 2, 3, 4, 5, 6, 7, 8, 9}
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// filter even numbers from the slice
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evens := u.Filter(numbers, func(n int) bool { return n%2 == 0 })
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// square every number in the slice
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squares := u.Map(evens, func(n int) int { return n * n })
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// reduce to the sum
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res := u.Reduce(squares, func(n, acc int) int { return n + acc }, 0)
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fmt.Println(res) // 120
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}
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```
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## Getting Started
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These instructions will get you a copy of the project up and running on your local
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machine for development and testing purposes.
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### Prerequisites
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You need at least `go1.24` for development. The project is shipped with a [Dockerfile](Dockerfile)
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based on `go1.24`.
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If you prefer local development, navigate to the [official
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download page](https://go.dev/dl/) and install version `1.24` or beyond.
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### Installing
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First clone the repository
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```sh
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git clone https://github.com/rjNemo/underscore.git
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```
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Install dependencies
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```sh
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go mod download
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```
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And that's it.
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## Tests
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To run the unit tests, you can simply run:
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```sh
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make test
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```
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## Functions
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`underscore` provides many of functions that support your favorite functional helpers
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### Collections
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- `All`
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- `Any`
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- `Chunk`
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- `Contains`
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- `ContainsBy`
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- `Count`
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- `Difference`
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- `Drop`
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- `Each`
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- `Filter`
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- `Find`
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- `Flatmap`
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- `GroupBy`
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- `Intersection`
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- `Join` / `JoinProject`
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- `Last`
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- `Map`
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- `Max`
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- `Min`
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- `OrderBy`
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- `Partition`
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- `Range`
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- `Reduce`
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- `RemoveAt`
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- `Sum` / `SumMap`
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- `Unique`
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- `UniqueBy`
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- `UniqueInPlace`
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- `Zip`
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### Pipe
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Calling `NewPipe` will cause all future method calls to return wrapped values. When
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you've finished the computation, call `Value` to retrieve the final value.
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Methods not returning a slice such as `Reduce`, `All`, `Any`, will break the `Chain`
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and return `Value` instantly.
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### Concurrency
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- `ParallelMap(ctx, values, workers, fn)`: apply a function concurrently while preserving order and supporting context cancellation.
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- `ParallelFilter(ctx, values, workers, fn)`: filter concurrently with order preserved and context support.
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```go
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package main
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import (
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"context"
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"fmt"
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u "github.com/rjNemo/underscore"
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)
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func main() {
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out, err := u.ParallelMap(context.Background(), []int{1, 2, 3, 4}, 4,
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func(ctx context.Context, n int) (int, error) { return n * n, nil },
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)
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fmt.Println(out, err) // [1 4 9 16] <nil>
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}
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```
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```go
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// ParallelFilter example
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package main
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import (
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"context"
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"fmt"
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u "github.com/rjNemo/underscore"
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)
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func main() {
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out, err := u.ParallelFilter(context.Background(), []int{1,2,3,4,5}, 3,
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func(ctx context.Context, n int) (bool, error) { return n%2==0, nil },
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)
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fmt.Println(out, err) // [2 4] <nil>
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}
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```
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### Utilities
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- `Ternary`: conditional expression helper
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- `ToPointer`: convert values to pointers
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- `SortSliceASC` / `SortSliceDESC`: sort slices in ascending or descending order
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- `Result`, `Ok`, `Err`, `ToResult`: Result type for error handling
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- `Tuple`: generic tuple type for paired values
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### Subpackages
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- `maps.Keys(m)` / `maps.Values(m)`: extract keys or values from maps
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- `maps.Map(m, fn)`: transform map entries
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## Built With
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- [Go](https://go.dev/) - Build fast, reliable, and efficient software at scale
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## Contributing
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Please read [CONTRIBUTING.md](CONTRIBUTING.md) for details on our code of conduct,
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and the process for submitting pull requests to us.
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## Versioning
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We use [SemVer](http://semver.org/) for versioning. For the versions available, see
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the [tags on this repository](https://github.com/rjNemo/underscore/tags).
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## Authors
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- **Ruidy** - _Initial work_ - [Ruidy](https://github.com/rjNemo)
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See also the list of [contributors](https://github.com/rjNemo/underscore/contributors)
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who participated in this project.
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## License
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This project is licensed under the MIT License - see the [LICENSE.md](LICENSE.md)
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file for details
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## Acknowledgments
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This project is largely inspired by [Underscore.js](https://underscorejs.org/#)
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library. Check out the original project if you don't already know it.
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