Gophers - generic collection utils for Go

Gophers is an awesome collections library for Go offering tons of utilities right out of the box.

Collection Types:

• Sequence : An ordered collection wrapping a Go slice. Great for fast random access.
• ComparableSequence : A Sequence of comparable elements. Offers extra functionality.
• List : An ordered collection wrapping a linked list. Great for fast insertion, removal, and implementing stacks and queues.
• ComparableList : A List of comparable elements. Offers extra functionality.
• Set : A hash set of unique elements.

Here's a few examples of what you can do:

Quick Start

Installation

go get github.com/charbz/gophers

Using Generic Data Types

import (
  "github.com/charbz/gophers/list"
)

type Foo struct {
  a int
  b string
}

foos := list.NewList([]Foo{
  {a: 1, b: "one"}, 
  {a: 2, b: "two"}, 
  {a: 3, b: "three"}, 
  {a: 4, b: "four"}, 
  {a: 5, b: "five"},
})

foos.Filter(func(f Foo) bool { return f.a%2 == 0 }) 
// List[Foo] {{2 two} {4 four}}

foos.Reject(func(f Foo) bool { return f.a%2 == 0 }) 
// List[Foo] {{1 one} {3 three} {5 five}}

foos.Find(func(f Foo) bool { return f.a == 3 }) 
// {a: 3, b: "three"}

foos.Partition(func(f Foo) bool { return len(f.b) == 3 })
// List[Foo] {{1 one} {2 two}} , List[Foo] {{3 three} {4 four} {5 five}}

foos.SplitAt(3) 
// List[Foo] {{1 one} {2 two} {3 three} {4 four}} , List[Foo] {{5 five}}

foos.Count(func(f Foo) bool { return f.a < 3 }) 
// 2

bars := foos.Concat(list.NewList([]Foo{{a: 1, b: "one"}, {a: 2, b: "two"}})) 
// List[Foo] {{1 one} {2 two} {3 three} {4 four} {5 five} {1 one} {2 two}}

bars.Distinct(func(i Foo, j Foo) bool { return i.a == j.a }) 
// List[Foo] {{1 one} {2 two} {3 three} {4 four} {5 five}}

foos.Apply(
  func(f Foo) Foo {
    f.a *= 2
    f.b += " * two"
    return f
  }
)
// List[Foo] {{2 one * two} {4 two * two} {6 three * two} {8 four * two} {10 five * two}}

Comparable Collections

Comparable collections are collections with elements that can be compared to each other. They offer all the same functionality as an ordered collection but provide additional convenience methods.

import (
  "github.com/charbz/gophers/list"
)

nums := list.NewComparableList([]int{1, 1, 2, 2, 2, 3, 4, 5})

nums.Max() // 5

nums.Min() // 1

nums.Sum() // 20

nums.Distinct() // List[int] {1,2,3,4,5}

nums.Reverse() // List[int] {5,4,3,2,2,1,1}

nums.SplitAt(3) // List[int] {1,1,2,2}, List[int] {2,3,4,5}

nums.Take(3) // List[int] {1,1,2}

nums.TakeRight(3) // List[int] {3,4,5}

nums.Drop(3) // List[int] {2,2,3,4,5}

nums.DropRight(3) // List[int] {1,1,2,2,2}

nums.DropWhile(
  func(i int) bool { return i < 3 }, // List[int] {3,4,5}
)

nums.Diff(
  list.NewComparableList([]int{1, 2, 3}), // List[int] {4,5}
)

nums.Count(
  func(i int) bool { return i > 2 }, // 3
)

Sets

Sets are collections of unique elements. They offer all the same functionality as an unordered collection but provide additional methods for set operations.

import (
  "github.com/charbz/gophers/set"
)

setA := set.NewSet([]string{"A", "B", "C", "A", "C", "A"}) // Set[string] {"A", "B", "C"}
setB := set.NewSet([]string{"A", "B", "D"})

setA.Intersection(setB) // Set[string] {"A", "B"}

setA.Union(setB) // Set[string] {"A", "B", "C", "D"}

setA.Diff(setB) // Set[string] {"C"}

setA.Apply(
  func(s string) string {
    s += "!"
    return s
  }, // Set[string] {"A!", "B!", "C!"}
)

Map, Reduce, GroupBy...

You can use package functions such as Map, Reduce, GroupBy, and many more on any concrete collection type.

import (
  "github.com/charbz/gophers/collection"
  "github.com/charbz/gophers/list"
  "github.com/charbz/gophers/sequence"
)

foos := sequence.NewSequence([]Foo{
	{a: 1, b: "one"},
	{a: 2, b: "two"},
	{a: 3, b: "three"},
	{a: 4, b: "four"},
	{a: 5, b: "five"},
})

collection.Map(foos, func(f Foo) string { return f.b }) //  ["one", "two", "three", "four", "five"] 

collection.Reduce(foos, func(acc string, f Foo) string { return acc + f.b }, "") // "onetwothreefourfive"

collection.Reduce(foos, func(acc int, f Foo) int { return acc + f.a }, 0) // 15

collection.GroupBy(foos, func(f Foo) int { return f.a % 2 }) // Map[int][]Foo { 0: [{2 two}, {4 four}], 1: [{1 one}, {3 three}, {5 five}]}

Note: Given that methods cannot define new type parameters in Go, any function that produces a new type, for example Map(List[T], func(T) K) -> List[K], must be called as a function similar to the examples above and cannot be made into a method of the collection type i.e. List[T].Map(func(T) K) -> List[K]. This is a minor inconvenience as it breaks the consistency of the API but is a limitation of the language.

Iterator Methods

All collections implement methods that return iterators over the result as opposed to returning the result itself. This is useful when combined with the for ... range syntax to iterate over the result.

import (
  "github.com/charbz/gophers/list"
)

A := list.NewComparableList([]int{1, 2, 2, 3})
B := list.NewComparableList([]int{4, 5, 2})

for i := range A.Filtered(func(v int) bool { return v%2 == 0 }) {
  fmt.Printf("filtered %v\n", i)
}
// filtered 2
// filtered 2

for i := range A.Rejected(func(v int) bool { return v%2 == 0 }) {
  fmt.Printf("rejected %v\n", i)
}
// rejected 1
// rejected 3

for i := range A.Distincted() {
  fmt.Printf("distincted %v\n", i)
}
// distincted 1
// distincted 2
// distincted 3

for i := range A.Concatenated(B) {
  fmt.Printf("concatenated %v\n", i)
}
// concatenated 1
// concatenated 2
// concatenated 2
// concatenated 3
// concatenated 4
// concatenated 5
// concatenated 2

for i := range A.Diffed(B) {
  fmt.Printf("diffed %v\n", i)
}
// diffed 1
// diffed 3

for i := range A.Intersected(B) {
  fmt.Printf("intersected %v\n", i)
}
// intersected 2
// intersected 2    // (A is not a set)

Sequence Operations

• Add(element) - Append element to sequence
• All() - Get iterator over all elements
• At(index) - Get element at index
• Apply(function) - Apply function to each element (mutates the original collection)
• Backward() - Get reverse iterator over elements
• Clone() - Create shallow copy of sequence
• Concat(sequences...) - Concatenates any passed sequences
• Concatenated(sequence) - Get iterator over concatenated sequence
• Contains(predicate) - Test if any element matches predicate
• Corresponds(sequence, function) - Test element-wise correspondence
• Count(predicate) - Count elements matching predicate
• Dequeue() - Remove and return first element
• Diff(sequence, function) - Get elements in first sequence but not in second
• Diffed(sequence, function) - Get iterator over elements in first sequence but not in second
• Distinct(function) - Get unique elements using equality function
• Distincted() - Get unique elements using equality comparison
• Drop(n) - Drop first n elements
• DropRight(n) - Drop last n elements
• DropWhile(predicate) - Drop elements while predicate is true
• Enqueue(element) - Add element to end
• Equals(sequence, function) - Test sequence equality using function
• Exists(predicate) - Test if any element matches predicate
• Filter(predicate) - Filter elements based on predicate
• FilterNot(predicate) - Inverse filter operation
• Find(predicate) - Find first matching element
• FindLast(predicate) - Find last matching element
• ForAll(predicate) - Test if predicate holds for all elements
• Head() - Get first element
• Init() - Get all elements except last
• Intersect(sequence, function) - Get elements present in both sequences
• Intersected(sequence, function) - Get iterator over elements present in both sequences
• IsEmpty() - Test if sequence is empty
• Last() - Get last element
• Length() - Get number of elements
• New(slices...) - Create new sequence
• NewOrdered(slices...) - Create new ordered sequence
• NonEmpty() - Test if sequence is not empty
• Partition(predicate) - Split sequence based on predicate
• Pop() - Remove and return last element
• Push(element) - Add element to end
• Random() - Get random element
• Reverse() - Reverse order of elements
• Reject(predicate) - Inverse filter operation
• Rejected(predicate) - Get iterator over elements rejected by predicate
• Slice(start, end) - Get subsequence from start to end
• SplitAt(n) - Split sequence at index n
• String() - Get string representation
• Take(n) - Get first n elements
• TakeRight(n) - Get last n elements
• Tail() - Get all elements except first
• ToSlice() - Convert to Go slice
• Values() - Get iterator over values

ComparableSequence Operations

Inherits all operations from Sequence, but with the following additional operations:

• Contains(element) - Test if sequence contains element
• Distinct() - Get unique elements using equality comparison
• Diff(sequence) - Get elements in first sequence but not in second
• Equals(sequence) - Test sequence equality using equality comparison
• Exists(element) - Test if sequence contains element
• IndexOf(element) - Get index of first occurrence of element
• LastIndexOf(element) - Get index of last occurrence of element
• Max() - Get maximum element
• Min() - Get minimum element
• Sum() - Get sum of all elements

List Operations

• Add(element) - Add element to end
• All() - Get iterator over index/value pairs
• Apply(function) - Apply function to each element
• At(index) - Get element at index
• Backward() - Get reverse iterator over index/value pairs
• Clone() - Create shallow copy
• Concat(lists...) - Concatenate multiple lists
• Concatenated(list) - Get iterator over concatenated list
• Contains(predicate) - Test if any element matches predicate
• Corresponds(list, function) - Test element-wise correspondence
• Count(predicate) - Count elements matching predicate
• Dequeue() - Remove and return first element
• Diff(list, function) - Get elements in first list but not in second
• Diffed(list, function) - Get iterator over elements in first list but not in second
• Distinct(function) - Get unique elements using equality function
• Distincted() - Get unique elements using equality comparison
• Drop(n) - Drop first n elements
• DropRight(n) - Drop last n elements
• DropWhile(predicate) - Drop elements while predicate is true
• Enqueue(element) - Add element to end
• Equals(list, function) - Test list equality using function
• Exists(predicate) - Test if any element matches predicate
• Filter(predicate) - Filter elements based on predicate
• FilterNot(predicate) - Inverse filter operation
• Find(predicate) - Find first matching element
• FindLast(predicate) - Find last matching element
• ForAll(predicate) - Test if predicate holds for all elements
• Head() - Get first element
• Init() - Get all elements except last
• Intersect(list, function) - Get elements present in both lists
• Intersected(list, function) - Get iterator over elements present in both lists
• IsEmpty() - Test if list is empty
• Last() - Get last element
• Length() - Get number of elements
• New(slices...) - Create new list
• NewOrdered(slices...) - Create new ordered list
• NonEmpty() - Test if list is not empty
• Partition(predicate) - Split list based on predicate
• Pop() - Remove and return last element
• Push(element) - Add element to end
• Random() - Get random element
• Reverse() - Reverse order of elements
• Reject(predicate) - Inverse filter operation
• Rejected(predicate) - Get iterator over elements rejected by predicate
• Slice(start, end) - Get sublist from start to end
• SplitAt(n) - Split list at index n
• String() - Get string representation
• Take(n) - Get first n elements
• TakeRight(n) - Get last n elements
• Tail() - Get all elements except first
• ToSlice() - Convert to Go slice
• Values() - Get iterator over values

ComparableList Operations

Inherits all operations from List, but with the following additional operations:

• Contains(value) - Test if list contains value
• Distinct() - Get unique elements
• Diff(list) - Get elements in first list but not in second
• Exists(value) - Test if list contains value (alias for Contains)
• Equals(list) - Test list equality
• IndexOf(value) - Get index of first occurrence of value
• LastIndexOf(value) - Get index of last occurrence of value
• Max() - Get maximum element
• Min() - Get minimum element
• Sum() - Get sum of all elements

Set Operations

• Add(element) - Add element to set
• Apply(function) - Apply function to each element
• Clone() - Create shallow copy of set
• Contains(value) - Test if set contains value
• ContainsFunc(predicate) - Test if set contains element matching predicate
• Count(predicate) - Count elements matching predicate
• Diff(set) - Get elements in first set but not in second
• Diffed(set) - Get iterator over elements in first set but not in second
• Equals(set) - Test set equality
• Filter(predicate) - Filter elements based on predicate
• FilterNot(predicate) - Inverse filter operation
• ForAll(predicate) - Test if predicate holds for all elements
• Intersection(set) - Get elements present in both sets
• Intersected(set) - Get iterator over elements present in both sets
• IsEmpty() - Test if set is empty
• Length() - Get number of elements
• New(slices...) - Create new set
• NonEmpty() - Test if set is not empty
• Partition(predicate) - Split set based on predicate
• Random() - Get random element
• Remove(element) - Remove element from set
• Reject(predicate) - Inverse filter operation
• Rejected(predicate) - Get iterator over elements rejected by predicate
• String() - Get string representation
• ToSlice() - Convert to Go slice
• Union(set) - Get elements present in either set
• Unioned(set) - Get iterator over elements present in either set
• Values() - Get iterator over values

Collection Functions

The following package functions can be called on any collection, including Sequence, ComparableSequence, List, ComparableList, and Set.

• Count(collection, predicate) - Count elements matching predicate
• Diff(collection) - Get elements in first collection but not in second
• Distinct(collection, function) - Get unique elements
• Filter(collection, predicate) - Filter elements based on predicate
• FilterNot(collection, predicate) - Inverse filter operation
• ForAll(collection, predicate) - Test if predicate holds for all elements
• GroupBy(collection, function) - Group elements by key function
• Intersect(collection1, collection2) - Get elements present in both collections
• Map(collection, function) - Transform elements using function
• MaxBy(collection, function) - Get maximum element by comparison function
• MinBy(collection, function) - Get minimum element by comparison function
• Partition(collection, predicate) - Split collection based on predicate
• Reduce(collection, function, initial) - Reduce collection to single value

The package functions below can be called on ordered collections (Sequence, ComparableSequence, List, and ComparableList):

• Corresponds(collection1, collection2, function) - test whether values in collection1 map into values in collection2 by the given function
• Drop(collection, n) - Drop first n elements
• DropRight(collection, n) - Drop last n elements
• DropWhile(collection, predicate) - Drop elements while predicate is true
• Find(collection, predicate) - returns the index and value of the first element matching predicate
• FindLast(collection, predicate) - returns the index and value of the last element matching predicate
• Head(collection) - returns the first element in a collection
• Init(collection) - returns all elements excluding the last one
• Last(collection) - Get last element
• ReduceRight(collection, function, initial) - Right-to-left reduction
• Reverse(collection) - Reverse order of elements
• ReverseMap(collection, function) - Map elements in reverse order
• SplitAt(collection, n) - Split collection at index n
• Tail(collection) - Get all elements except first
• Take(collection, n) - Get first n elements
• TakeRight(collection, n) - Get last n elements

The following package functions return an iterator for the result:

• Concatenated(collection1, collection2) - Get iterator over concatenated collection
• Diffed(collection1, collection2, function) - Get iterator over elements in first collection but not in second
• Intersected(collection1, collection2, function) - Get iterator over elements present in both collections
• Mapped(collection, function) - Get iterator over elements transformed by function
• Rejected(collection, predicate) - Get iterator over elements rejected by predicate

Contributing

Contributions are welcome! Feel free to submit a Pull Request.

If you have any ideas for new features or improvements, or would like to chat,

Feel free to reach out on Discord: Gophers Project or on Reddit: r/gopherslib