go-ienumerable

Golang's IEnumerable[T]

with inspiration from C#'s famous IEnumerable<T>

go-ienumerable

Code coverage: 100%

Require: Go 1.18+

Check the methods ported from C# IEnumerable[T] here in the enumerable interface definition

If you are new to IEnumerable, you can [explore & read examples by Microsoft](ported from C#).

got := goe.NewIEnumerable[string]("Hello", "World").
    Where(func(v string) bool {
        return len(v) < 3
    }).
    OrderDescending().GetOrderedEnumerable().
    Reverse().
    FirstOrDefault(nil, goe.Ptr("Oops"))

fmt.Println(got)
// "Oops"

array := []byte{0, 70, 99, 106, 106, 109, 30, 85, 109, 112, 106, 98, 99, 66, 88, 69}
got := goe.NewIEnumerable[byte](array...).
    Skip(1).
    Take(11).
    Select(transform).
    CastInt32().
    Append('"').
    AggregateAnySeed("\"", aggregate)

fmt.Println(got)
// "Hello World"

Notice about some missing methods:

Due to limitation of Go that does not allow generic type in struct method, the following methods are defined in goe_helper package as utility methods, instead of attaching directly into the IEnumerable instance:

• Chunk
• GroupBy
• GroupJoin
• Join
• OfType
• Zip

Example: ❌ instance.Chunk(size:2) | ✅ goe_helper.Chunk(instance, size:2)

The following methods are implemented IEnumerable instance but also implemented in goe_helper package, since methods in helper package is more likely C# method signature.

• Select
• SelectMany
• Aggregate
• Empty
• Repeat

Notices about value comparison:

Some IEnumerable[T] methods like Order, Distinct, Except, Union, Intersect,... need value comparator to compare between each element in the sequence and the IComparer[T] is needed.

This is definition of IComparer[T] in comparers package:

// IComparer use methods Compare* to compare value of 2 input values.
//
// If left is less than right, returns -1.
//
// If left is equals to right, returns 0.
//
// If left is greater than right, returns 1.
type IComparer[T any] interface {
    // CompareTyped compares value from params.
    //
    // If x is less than y, returns -1.
    //
    // If x is equals to y, returns 0.s
    //
    // If x is greater than y, returns 1.
    CompareTyped(x, y T) int

    // CompareAny accept any params.
    //
    // If both x and y are nil, return 0.
    //
    // If x is nil and y is not nil, return -1.
    //
    // If x is not nil and y is nil, return 1.
    //
    // The rest, implement in your own way, since type any means you can pass everything here,
    // and you should handle them carefully
    CompareAny(x, y any) int
}

See implementation sample in example.

go-ienumerable will attempts to resolve a default comparer using predefined comparers for some type. You can register a comparer for YourType by implement your own IComparer[YourType]. See sample of implement and default comparer registration for custom types and other types in example.

Predefined IComparer[T]: string, bool, numeric (int, int8/16/32/64, uint, uint8/16/32/64, float32/64, complex64/128), *big.Int, *big.Float, time.Time with corresponding initialized comparer instance, eg: compares.StringComparer is a string comparer, compares.NumericComparer is comparer of numeric and so on.