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just

This project is contains functions that help to do noizy things in every project.

• Filter slices, maps.
• Apply functions to collections.
• Null[any] for optional fields in api an sql.DB requests.

Documentation

Index

• func Abs[T number](v T) T
• func Bool[T builtin](v T) bool
• func ChanAdapt[T, D any](in <-chan T, fn func(T) D) <-chan D
• func ChanPut[T any](ch chan T, elems []T)
• func ChanReadN[T any](ch chan T, n int) []T
• func ErrIsAnyOf(err error, errSlice ...error) bool
• func ErrIsNotAnyOf(err error, errSlice ...error) bool
• func MapApply[K comparable, V any](in map[K]V, fn func(k K, v V))
• func MapContainsKey[K comparable, V any](m map[K]V, key K) bool
• func MapContainsKeysAll[K comparable, V any](m map[K]V, keys []K) bool
• func MapContainsKeysAny[K comparable, V any](m map[K]V, keys []K) bool
• func MapCopy[K comparable, V any](m map[K]V) map[K]V
• func MapDefaults[K comparable, V any](m map[K]V, defaults map[K]V) map[K]V
• func MapFilter[K comparable, V any](in map[K]V, fn func(k K, v V) bool) map[K]V
• func MapFilterKeys[K comparable, V any](in map[K]V, fn func(k K) bool) map[K]V
• func MapFilterValues[K comparable, V any](in map[K]V, fn func(v V) bool) map[K]V
• func MapGetKeys[K comparable, V any](m map[K]V) []K
• func MapGetValues[K comparable, V any](m map[K]V) []V
• func MapMap[K, K1 comparable, V, V1 any](in map[K]V, fn func(K, V) (K1, V1)) map[K1]V1
• func MapMapErr[K, K1 comparable, V, V1 any](in map[K]V, fn func(K, V) (K1, V1, error)) (map[K1]V1, error)
• func MapMerge[K comparable, V any](m1, m2 map[K]V, fn func(k K, v1, v2 V) V) map[K]V
• func Max[T number](in ...T) T
• func MaxDefault[T number](in ...T) T
• func MaxOr[T number](defaultVal T, in ...T) T
• func Min[T number](in ...T) T
• func MinDefault[T number](in ...T) T
• func MinOr[T number](defaultVal T, in ...T) T
• func Must[T any](val T, err error) T
• func Pointer[T any](v T) *T
• func PointerUnwrap[T any](in *T) T
• func Slice2Chan[T any](in []T, capacity int) chan T
• func Slice2ChanFill[T any](in []T) chan T
• func Slice2Map[T comparable](in []T) map[T]struct{}
• func Slice2MapFn[T any, K comparable, V any](in []T, fn func(idx int, elem T) (K, V)) map[K]V
• func Slice2MapFnErr[T any, K comparable, V any](in []T, fn func(idx int, elem T) (K, V, error)) (map[K]V, error)
• func SliceAddNotExists[T comparable](in []T, elem T) []T
• func SliceAll[T any](in []T, fn func(T) bool) bool
• func SliceAny[T any](in []T, fn func(T) bool) bool
• func SliceApply[T any](in []T, fn func(int, T))
• func SliceChain[T any](in ...[]T) []T
• func SliceChunk[T any](in []T, fn func(i int, elem T) bool) [][]T
• func SliceChunkEvery[T any](in []T, every int) [][]T
• func SliceContainsElem[T comparable](in []T, elem T) bool
• func SliceDifference[T comparable](oldSlice, newSlice []T) []T
• func SliceEqualUnordered[T comparable](in1, in2 []T) bool
• func SliceFillElem[T any](l int, elem T) []T
• func SliceFilter[T any](in []T, fn func(T) bool) []T
• func SliceFindAllElements[T any](in []T, fn func(i int, elem T) bool) []T
• func SliceFindAllIndexes[T any](in []T, fn func(i int, elem T) bool) []int
• func SliceFromElem[T any](elem T) []T
• func SliceGetFirstN[T any](in []T, maxElems int) []T
• func SliceGroupBy[K comparable, V any](in []V, fn func(V) K) map[K][]V
• func SliceIntersection[T comparable](oldSlice, newSlice []T) []T
• func SliceMap[T any, V any](in []T, fn func(T) V) []V
• func SliceMapErr[T any, V any](in []T, fn func(T) (V, error)) ([]V, error)
• func SliceRange[T number](start, stop, step T) []T
• func SliceReverse[T any](in []T) []T
• func SliceSort[T any](in []T, less func(a, b T) bool)
• func SliceSortCopy[T any](in []T, less func(a, b T) bool) []T
• func SliceUnion[T comparable](in ...[]T) []T
• func SliceUniq[T comparable](in []T) []T
• func SliceWithout[T any](in []T, fn func(T) bool) []T
• func SliceWithoutElem[T comparable](in []T, elem T) []T
• func SliceZip[T any](in ...[]T) [][]T
• func Sum[T number](in ...T) T
• type KV
  • func MapPairs[K comparable, V any](m map[K]V) []KV[K, V]
• type NullVal
  • func Null[T any](val T) NullVal[T]
  • func NullNull[T any]() NullVal[T]
  • func (nv *NullVal[T]) Scan(value any) error
  • func (nv *NullVal[T]) SetDefault(val T) bool
  • func (nv NullVal[T]) Value() (driver.Value, error)
  • func (nv NullVal[T]) ValueOk() (T, bool)
• type SliceElem
  • func SliceFindAll[T any](in []T, fn func(i int, elem T) bool) []SliceElem[T]
  • func SliceFindFirst[T any](in []T, fn func(i int, elem T) bool) SliceElem[T]
  • func SliceFindFirstElem[T comparable](in []T, elem T) SliceElem[T]
  • func SliceFindLast[T any](in []T, fn func(i int, elem T) bool) SliceElem[T]
  • func SliceFindLastElem[T comparable](in []T, elem T) SliceElem[T]
  • func (e SliceElem[T]) Ok() bool
  • func (e SliceElem[T]) ValueIdx() (T, int)
  • func (e SliceElem[T]) ValueOk() (T, bool)

Examples

• Must

Functions

func Abs

func Abs[T number](v T) T

Abs returns abs value of v.

func Bool

func Bool[T builtin](v T) bool

Bool returns true if element not equal to default value for this type.

func ChanAdapt

func ChanAdapt[T, D any](in <-chan T, fn func(T) D) <-chan D

ChanAdapt returns a channel, which will contains adapted messages from source channel. Result channel will closed after source channel is closed.

func ChanPut

func ChanPut[T any](ch chan T, elems []T)

ChanPut will put all elements into the channel synchronously.

func ChanReadN

func ChanReadN[T any](ch chan T, n int) []T

ChanReadN will read N messages from channel and return the result slice.

func ErrIsAnyOf

func ErrIsAnyOf(err error, errSlice ...error) bool

ErrIsAnyOf return true when at least one expression `errors.Is(err, errSlice[N])` return true.

func ErrIsNotAnyOf

func ErrIsNotAnyOf(err error, errSlice ...error) bool

ErrIsNotAnyOf return true when all errors from errSlice is not `errors.Is(err, errSlice[N])`.

func MapApply

func MapApply[K comparable, V any](in map[K]V, fn func(k K, v V))

MapApply apply fn to each kv pair

func MapContainsKey

func MapContainsKey[K comparable, V any](m map[K]V, key K) bool

MapContainsKey returns true if key is exists in the map.

func MapContainsKeysAll

func MapContainsKeysAll[K comparable, V any](m map[K]V, keys []K) bool

MapContainsKeysAll returns true when at all keys exists in the map.

func MapContainsKeysAny

func MapContainsKeysAny[K comparable, V any](m map[K]V, keys []K) bool

MapContainsKeysAny returns true when at least one key exists in the map.

func MapCopy

func MapCopy[K comparable, V any](m map[K]V) map[K]V

MapCopy returns a shallow copy of map.

func MapDefaults

func MapDefaults[K comparable, V any](m map[K]V, defaults map[K]V) map[K]V

MapDefaults returns the map `m` after filling in its non-exists keys by `defaults`. Example: {1:1}, {1:0, 2:2} => {1:1, 2:2}

func MapFilter

func MapFilter[K comparable, V any](in map[K]V, fn func(k K, v V) bool) map[K]V

MapFilter returns the map which contains elements that `fn(key, value) == true`.

func MapFilterKeys

func MapFilterKeys[K comparable, V any](in map[K]V, fn func(k K) bool) map[K]V

MapFilterKeys returns the map which contains elements that `fn(key) == true`. That is a simplified version of MapFilter.

func MapFilterValues

func MapFilterValues[K comparable, V any](in map[K]V, fn func(v V) bool) map[K]V

MapFilterValues returns the map which contains elements that `fn(value) == true`. That is a simplified version of MapFilter.

func MapGetKeys

func MapGetKeys[K comparable, V any](m map[K]V) []K

MapGetKeys returns all keys of map.

func MapGetValues

func MapGetValues[K comparable, V any](m map[K]V) []V

MapGetValues returns all values of map. Not Uniq, unordered.

func MapMap

func MapMap[K, K1 comparable, V, V1 any](in map[K]V, fn func(K, V) (K1, V1)) map[K1]V1

MapMap apply fn to all kv pairs from in.

func MapMapErr

func MapMapErr[K, K1 comparable, V, V1 any](in map[K]V, fn func(K, V) (K1, V1, error)) (map[K1]V1, error)

MapMapErr apply fn to all kv pairs from in.

func MapMerge

func MapMerge[K comparable, V any](m1, m2 map[K]V, fn func(k K, v1, v2 V) V) map[K]V

MapMerge returns the map which contains all keys from m1, m2 and values from `fn(key, m1Value, m2Value)`.

func Max

func Max[T number](in ...T) T

Max returns the max number from `in`.

func MaxDefault

func MaxDefault[T number](in ...T) T

MaxDefault returns max element from `in` or default value for specified type when `in` is empty.

func MaxOr

func MaxOr[T number](defaultVal T, in ...T) T

MaxOr returns max element from `in` or defaultVal when `in` is empty

func Min

func Min[T number](in ...T) T

Min returns the min number from `in`.

func MinDefault

func MinDefault[T number](in ...T) T

MinDefault returns min element from `in` or default value for specified type when `in` is empty.

func MinOr

func MinOr[T number](defaultVal T, in ...T) T

MinOr returns min element from `in` or defaultVal when `in` is empty

func Must

func Must[T any](val T, err error) T

Must will panic on error after calling typical function.

Example

package main

import (
	"bytes"
	"fmt"
	"github.com/kazhuravlev/just"
	"io"
)

func main() {
	val := just.Must(io.ReadAll(bytes.NewBufferString("this is body!")))
	fmt.Println(string(val))
}

Output:

this is body!

func Pointer

func Pointer[T any](v T) *T

Pointer return a pointer to `v`.

func PointerUnwrap

func PointerUnwrap[T any](in *T) T

PointerUnwrap returns value from pointer.

func Slice2Chan

func Slice2Chan[T any](in []T, capacity int) chan T

Slice2Chan make chan with specified capacity from source slice.

func Slice2ChanFill

func Slice2ChanFill[T any](in []T) chan T

Slice2ChanFill make chan from source slice with will already filled by all elements from source slice.

func Slice2Map

func Slice2Map[T comparable](in []T) map[T]struct{}

Slice2Map make map from slice, which contains all values from `in` as map keys.

func Slice2MapFn

func Slice2MapFn[T any, K comparable, V any](in []T, fn func(idx int, elem T) (K, V)) map[K]V

Slice2MapFn apply fn to every elem. fn should return key and value, which will be applied to result map.

func Slice2MapFnErr

func Slice2MapFnErr[T any, K comparable, V any](in []T, fn func(idx int, elem T) (K, V, error)) (map[K]V, error)

Slice2MapFnErr apply fn to every elem. fn should return key and value, which will be applied to result map. return error when at least one fn returns an error.

func SliceAddNotExists

func SliceAddNotExists[T comparable](in []T, elem T) []T

SliceAddNotExists return `in` with `elem` inside when `elem` not exists in `in`.

func SliceAll

func SliceAll[T any](in []T, fn func(T) bool) bool

SliceAll returns true when `fn` returns true for all elements from `in`. Returns true when in is empty.

func SliceAny

func SliceAny[T any](in []T, fn func(T) bool) bool

SliceAny returns true when `fn` returns true for at least one element from `in`.

func SliceApply

func SliceApply[T any](in []T, fn func(int, T))

SliceApply handle all elements from `in` by function `fn`. Function apply sequentially.

func SliceChain

func SliceChain[T any](in ...[]T) []T

SliceChain returns a slice where all `in` slices id appended to the end. Like append(append(in[0], in[1]...), in[2]...).

func SliceChunk

func SliceChunk[T any](in []T, fn func(i int, elem T) bool) [][]T

SliceChunk split `in` into chunks by fn(index, elem) == true.

func SliceChunkEvery

func SliceChunkEvery[T any](in []T, every int) [][]T

SliceChunkEvery split `in` into chunks by size `every`

func SliceContainsElem

func SliceContainsElem[T comparable](in []T, elem T) bool

SliceContainsElem returns true when `in` contains elem.

func SliceDifference

func SliceDifference[T comparable](oldSlice, newSlice []T) []T

SliceDifference return the difference between `oldSlice` and `newSlice`. Returns only elements which presented in `newSlice` but not presented in `oldSlice`. Example: [1,2,3], [3,4,5,5,5] => [4,5,5,5]

func SliceEqualUnordered

func SliceEqualUnordered[T comparable](in1, in2 []T) bool

SliceEqualUnordered returns true when all uniq values from `in1` contains in `in2`. Useful in tests for comparing expected and actual slices. Examples:

• [1,2,3], [2,3,3,3,1,1] => true
• [1], [1,1,1] => true
• [1], [1] => true
• [1], [2] => false

func SliceFillElem

func SliceFillElem[T any](l int, elem T) []T

SliceFillElem returns the slice with len `l` where all elements are equal to `elem`.

func SliceFilter

func SliceFilter[T any](in []T, fn func(T) bool) []T

SliceFilter returns slice of values from `in` where `fn(elem) == true`.

func SliceFindAllElements

func SliceFindAllElements[T any](in []T, fn func(i int, elem T) bool) []T

SliceFindAllElements return all elem from `in` that fn(index, elem) == true.

func SliceFindAllIndexes

func SliceFindAllIndexes[T any](in []T, fn func(i int, elem T) bool) []int

SliceFindAllIndexes return all indexes from `in` that fn(index, elem) == true.

func SliceFromElem

func SliceFromElem[T any](elem T) []T

SliceFromElem return a slice which contains only one element `elem`.

func SliceGetFirstN

func SliceGetFirstN[T any](in []T, maxElems int) []T

SliceGetFirstN return a subslice of source slice, which will contains not more than `maxElems` items.

func SliceGroupBy

func SliceGroupBy[K comparable, V any](in []V, fn func(V) K) map[K][]V

SliceGroupBy will group all

func SliceIntersection

func SliceIntersection[T comparable](oldSlice, newSlice []T) []T

SliceIntersection returns elements that are presented in both slices. Example: [1,2,3], [2,4,3,3,3] => [2, 3]

func SliceMap

func SliceMap[T any, V any](in []T, fn func(T) V) []V

SliceMap returns the slice where each element of `in` was handled by `fn`.

func SliceMapErr

func SliceMapErr[T any, V any](in []T, fn func(T) (V, error)) ([]V, error)

SliceMapErr do the same thing as SliceMap, but return error when error occurs in fn.

func SliceRange

func SliceRange[T number](start, stop, step T) []T

SliceRange produces a sequence of integers from start (inclusive) to stop (exclusive) by step.

func SliceReverse

func SliceReverse[T any](in []T) []T

SliceReverse reverse the slice.

func SliceSort

func SliceSort[T any](in []T, less func(a, b T) bool)

SliceSort sort slice inplace.

func SliceSortCopy

func SliceSortCopy[T any](in []T, less func(a, b T) bool) []T

SliceSortCopy copy and sort slice.

func SliceUnion

func SliceUnion[T comparable](in ...[]T) []T

SliceUnion returns only uniq items from all slices.

func SliceUniq

func SliceUniq[T comparable](in []T) []T

SliceUniq returns only unique values from `in`.

func SliceWithout

func SliceWithout[T any](in []T, fn func(T) bool) []T

SliceWithout returns the slice `in` where fn(elem) == true.

func SliceWithoutElem

func SliceWithoutElem[T comparable](in []T, elem T) []T

SliceWithoutElem returns the slice `in` that not contains `elem`.

func SliceZip

func SliceZip[T any](in ...[]T) [][]T

SliceZip returns merged together the values of each of the arrays with the values at the corresponding position. If the len of `in` is different - will use smaller one.

func Sum

func Sum[T number](in ...T) T

Sum returns the sum of numbers from `in`.

Types

type KV

type KV[K comparable, V any] struct {
	Key K
	Val V
}

KV represents the key-value of map.

func MapPairs

func MapPairs[K comparable, V any](m map[K]V) []KV[K, V]

MapPairs returns slice of KV structs that contains ket-value pairs.

type NullVal

type NullVal[T any] struct {
	Val   T    `json:"v"`
	Valid bool `json:"ok"`
}

NullVal represent the nullable value for this type.

func Null

func Null[T any](val T) NullVal[T]

Null returns NullVal for `val` type, which are `NullVal.Valid == true`.

func NullNull

func NullNull[T any]() NullVal[T]

NullNull returns NullVal, which are `NullVal.Valid == false`.

func (*NullVal[T]) Scan

func (nv *NullVal[T]) Scan(value any) error

Scan implements the Scanner interface.

func (*NullVal[T]) SetDefault

func (nv *NullVal[T]) SetDefault(val T) bool

SetDefault set value `val` if NullVal.Valid == false.

func (NullVal[T]) Value

func (nv NullVal[T]) Value() (driver.Value, error)

Value implements the driver Valuer interface.

func (NullVal[T]) ValueOk

func (nv NullVal[T]) ValueOk() (T, bool)

ValueOk returns the NullVal.Val and NullVal.Valid.

type SliceElem

type SliceElem[T any] struct {
	// Idx is index of element in slice.
	Idx int
	// Val is value on slice by Idx index.
	Val T
}

SliceElem represent element of slice.

func SliceFindAll

func SliceFindAll[T any](in []T, fn func(i int, elem T) bool) []SliceElem[T]

SliceFindAll return all elem and index from `in` that fn(index, elem) == true.

func SliceFindFirst

func SliceFindFirst[T any](in []T, fn func(i int, elem T) bool) SliceElem[T]

SliceFindFirst return first elem from `in` that fn(index, elem) == true. returns index of found elem or -1 if elem not found.

func SliceFindFirstElem

func SliceFindFirstElem[T comparable](in []T, elem T) SliceElem[T]

SliceFindFirstElem return first elem from `in` that equals to `elem`.

func SliceFindLast

func SliceFindLast[T any](in []T, fn func(i int, elem T) bool) SliceElem[T]

SliceFindLast return last elem from `in` that fn(index, elem) == true. returns index of found elem or -1 if elem not found.

func SliceFindLastElem

func SliceFindLastElem[T comparable](in []T, elem T) SliceElem[T]

SliceFindLastElem return last elem from `in` that equals to `elem`.

func (SliceElem[T]) Ok

func (e SliceElem[T]) Ok() bool

Ok returns true if Idx is valid.

func (SliceElem[T]) ValueIdx

func (e SliceElem[T]) ValueIdx() (T, int)

ValueIdx returns value and index as is. Useful for this:

elem, idx := SliceFindFirstElem([]int{1,2,3}, 2).ValueIdx()

func (SliceElem[T]) ValueOk

func (e SliceElem[T]) ValueOk() (T, bool)

ValueOk returns the value and true (when element is exists in slice) or false in other case. Useful for cases like:

if elem, ok := SliceFindFirstElem([]int{1,2,3}, 2); ok{
	fmt.Println(elem)
}