funcy

func Filter ¶

func Filter[T any](sl []T, test func(T) bool) []T

Filter takes a slice of any type and a predicate function. It passes each slice item to the predicate function, and returns a slice of the items for which the predicate function returns true.

func FilterWithIndex ¶

func FilterWithIndex[T any](sl []T, test func(int, T) bool) []T

FilterWithIndex is like Filter, but the predicate function receives two arguments. The second argument is the slice item; the first argument is the item's index within the slice. FilterWithIndex returns a list of the items for which the predicate function returns true.

func Map ¶

func Map[T1, T2 any](sl []T1, transform func(T1) T2) []T2

Map runs each item in a slice through a transformation function, and returns a slice of the transformed items. The transformed items may be a different type from the input items, e.g. strings to ints using strconv.Atoi.

Note: For functions that return multiple values, like strconv.Atoi, wrap the function in another function that returns a single value, and pass the wrapper as the transformation function. The wrapper can handle errors, etc.:

result := Map(input, func(s string) int {
	i, err := strconv.Atoi(s)
	if err != nil {
		log.Fatal(err)
	}
	return i
})

func MustTranspose ¶

func MustTranspose[T any](sl [][]T) [][]T

MustTranspose calls Transpose and panics on error.

func Reduce ¶

func Reduce[T1, T2 any](sl []T1, startValue T2, fReduce func(T2, T1) T2) T2

Reduce reduces a slice to a single value by running each item of the slice through a function that takes an accumulator and the next item as its paramaters. The classic example is reducing a slice of numbers by adding them together.

func Sum ¶

func Sum[T constraints.Ordered](sl []T) T

Sum sums the items in a slice.

func Transpose ¶

func Transpose[T any](sl [][]T) ([][]T, error)

Transpose converts a matrix from T[rows][columns] to T[columns][rows]. The matrix cannot be jagged, i.e. all rows must have the same number of elements.