hofkit is a lightweight and idiomatic Go library providing functional programming utilities such as Map, Filter, Reduce, and more. It is designed to bring expressive, higher-order abstractions to Go while remaining performant and simple.

• Generic functions using Go 1.18+ type parameters
• Minimal allocations and performance close to native loops
• Fully benchmarked and tested

go get github.com/roman91DE/hofkit

Each function is generic and works with any type.

func Map[F any, T any](f func(F) T, xs []F) []T

Map applies function f to each element of the slice xs and returns a new slice with the results;

func Filter[T any](p func(T) bool, xs []T) []T

Filter applies predicate function p to each element of slice xs and returns a new slice with the elements that satisfy p;

func Reduce[F any, T any](f func(F, T) T, init T, xs []F) T

Reduce applies reducer function f to elements of slice xs, accumulating the result with initial value init, and returns the final result;

func All[T any](p func(T) bool, xs []T) bool

All applies predicate function p to each element of slice xs and returns true if all elements satisfy p;

func Any[T any](p func(T) bool, xs []T) bool

Any applies predicate function p to each element of slice xs and returns true if any element satisfies p;

func Find[T any](p func(T) bool, xs []T) (T, bool)

Find applies predicate function p to each element of slice xs and returns the first element that satisfies p and true; if no match is found, it returns the zero value and false;

func FindIndex[T any](p func(T) bool, xs []T) (int, bool)

FindIndex applies predicate function p to each element of slice xs and returns the index of the first match and true; if no match is found, it returns -1 and false;

func TakeWhile[T any](p func(T) bool, xs []T) []T

TakeWhile applies predicate function p to elements of slice xs and returns a new slice of leading elements that satisfy p;

func ForEach[T any](f func(T), xs []T)

ForEach applies function f to each element of slice xs for side effects;

func PartitionBy[T any](p func(T) bool, xs []T) ([]T, []T)

PartitionBy applies predicate function p to elements of slice xs and returns two slices: one with elements that satisfy p, and one with the rest;

func Partial1[A any, B any, R any](f func(A, B) R, a A) func(B) R

Partial1 takes a function (A, B) R and a value A, and returns func(B) R;

func Partial2[A any, B any, C any, R any](f func(A, B, C) R, a A, b B) func(C) R

Partial2 takes a function func(A, B, C) R and values A, B, and returns func(C) R;

func Partial3[A any, B any, C any, D any, R any](f func(A, B, C, D) R, a A, b B, c C) func(D) R

Partial3 takes a function func(A, B, C, D) R and values A, B, C, and returns func(D) R;

Benchmarks are located in the benchmark/ folder. They compare each hofkit function against an idiomatic native Go equivalent using:

go test -bench=. -benchmem

Plots and performance reports are generated with the Python script plot_bench.py.

Each benchmark is run on 10,000-element slices with non-trivial logic to stress CPU and memory.

Run all tests:

go test ./...

Pull requests welcome! This library is still young — feel free to open issues or suggest improvements.