Gogu is a versatile, comprehensive, reusable and efficient concurrent-safe utility functions and data structures library taking advantage of the Go generics. It was inspired by other well known and established frameworks like lodash or Apache Commons and some concepts being more closer to the functional programming paradigms.
Its main purpose is to facilitate the ease of working with common data structures like slices, maps and strings, through the implementation of many utility functions commonly used in the day-by-day jobs, but also integrating some of the most used data structure algorithms.
In what's different this library from other Go libraries exploring Go generics?
- It's concurrent-safe (with the exception of B-tree package)
- Implements a dozens of time related functions like:
before,after,delay,memoize,debounce,once,retry - Rich utility functions to operate with strings
- Very wide range of supported functions to deal with slice and map operations
- Extensive test coverage
- Implements the most used data structures
- Thourough documentation accompanied with examples
$ go get github.com/esimov/gogupackage main
import "github.com/esimov/gogu"
func main() {
// main program
}-
Generic Data Structures
bst: Binary Search Tree data structure implementation, where each node has at most two child nodes and the key of its internal node is greater than all the keys in the respective node's left subtree and less than the ones in the right subtreebtree: B-tree data structure implementation which is a self-balancing tree data structure maintaining its values in sorted ordercache: a basic in-memory key-value storage systemheap: Binary Heap data structure implementation where each node of the subtree is greather or equal then the parent nodelist: implements a singly and doubly linked list data structurequeue: package queue implements a FIFO (First-In-First-Out) data structure in two forms: using as storage system a resizing array and a doubly linked liststack: package stack implements a LIFO (Last-In-First-Out) data structure where the last element added to the stack is processed firsttrie: package trie provides a thread safe implementation of the ternary search tree data structure. Tries are used for locating specific keys from within a set or for quick lookup searches within a text like auto-completion or spell checking.
-
General utility functions
-
Strings utility functions
-
Slice utility functions
- Chunk
- SumBy
- Contains
- Difference
- DifferenceBy
- Drop
- DropWhile
- DropRightWhile
- Duplicate
- DuplicateWithIndex
- Every
- Filter
- FindAll
- FindIndex
- FindLastIndex
- FindMax
- FindMaxBy
- FindMaxByKey
- FindMin
- FindMinBy
- FindMinByKey
- Flatten
- ForEach
- ForEachRight
- GroupBy
- IndexOf
- Intersection
- IntersectionBy
- LastIndexOf
- Mean
- Merge
- Nth
- Partition
- PartitionMap
- Pluck
- Range
- RangeRight
- Reduce
- Reject
- Reverse
- Shuffle
- SliceToMap
- Some
- Sum
- SumBy
- ToSlice
- Union
- Unique
- UniqueBy
- Unzip
- Without
- Zip
-
Map utility functions
-
Concurrency and time related utility functions
func Abs
func Abs[T Number](x T) TAbs returns the absolut value of x.
func After
func After[V constraints.Signed](n *V, fn func())After creates a function wrapper that does nothing at first. From the nth call onwards, it starts actually invoking the callback function. Useful for grouping responses, where you need to be sure that all the calls have finished just before proceeding to the actual job.
Example
{
sample := []int{1, 2, 3, 4, 5, 6}
length := len(sample) - 1
initVal := 0
fn := func(val int) int {
return val + 1
}
ForEach(sample, func(val int) {
now := time.Now()
After(&length, func() {
<-time.After(10 * time.Millisecond)
initVal = fn(initVal)
after := time.Since(now).Milliseconds()
fmt.Println(after)
})
})
}10
func Before
func Before[S ~string, T any, V constraints.Signed](n *V, c *cache.Cache[S, T], fn func() T) TBefore creates a function wrapper that memoizes its return value. From the nth call onwards, the memoized result of the last invocation is returned immediately instead of invoking function again. So the wrapper will invoke function at most n-1 times.
Example
{
c := cache.New[string, int](cache.DefaultExpiration, cache.NoExpiration)
var n = 3
sample := []int{1, 2, 3}
ForEach(sample, func(val int) {
fn := func() int {
<-time.After(10 * time.Millisecond)
return n
}
res := Before(&n, c, fn)
// The trick to test this function is to decrease the n value after each iteration.
// We can be sure that the callback function is not served from the cache if n > 0.
// In this case the cache item "func" should be empty.
if n > 0 {
val, _ := c.Get("func")
fmt.Println(val)
fmt.Println(res)
}
if n <= 0 {
// Here the callback function is served from the cache.
val, _ := c.Get("func")
fmt.Println(val)
fmt.Println(res)
}
})
}<nil>
2
<nil>
1
&{0 0}
0
func CamelCase
func CamelCase[T ~string](str T) TCamelCase converts a string to camelCase (https://en.wikipedia.org/wiki/CamelCase\).
Example
{
fmt.Println(CamelCase("Foo Bar"))
fmt.Println(CamelCase("--foo-Bar--"))
fmt.Println(CamelCase("__foo-_Bar__"))
fmt.Println(CamelCase("__FOO BAR__"))
fmt.Println(CamelCase(" FOO BAR "))
fmt.Println(CamelCase("&FOO&baR "))
fmt.Println(CamelCase("&&foo&&bar__"))
}fooBar
fooBar
fooBar
fooBar
fooBar
fooBar
fooBar
func Capitalize
func Capitalize[T ~string](str T) TCapitalize converts the first letter of the string to uppercase and the remaining letters to lowercase.
func Chunk
func Chunk[T comparable](slice []T, size int) [][]TChunk split the slice into groups of slices each having the length of size. In case the source slice cannot be distributed equally, the last slice will contain fewer elements.
Example
{
fmt.Println(Chunk([]int{0, 1, 2, 3}, 2))
fmt.Println(Chunk([]int{0, 1, 2, 3, 4}, 2))
fmt.Println(Chunk([]int{0, 1}, 1))
}[[0 1] [2 3]]
[[0 1] [2 3] [4]]
[[0] [1]]
func Clamp
func Clamp[T Number](num, min, max T) TClamp returns a range-limited number between min and max.
func Compare
func Compare[T comparable](a, b T, comp CompFn[T]) intCompare compares two values using as comparator the callback function argument.
Example
{
res1 := Compare(1, 2, func(a, b int) bool {
return a < b
})
fmt.Println(res1)
res2 := Compare("a", "b", func(a, b string) bool {
return a > b
})
fmt.Println(res2)
}1
-1
func Contains
func Contains[T comparable](slice []T, value T) boolContains returns true if the value is present in the collection.
func Delay
func Delay(delay time.Duration, fn func()) *time.TimerDelay invokes the callback function with a predefined delay.
Example
{
ch := make(chan struct{})
now := time.Now()
var value uint32
timer := Delay(20*time.Millisecond, func() {
atomic.AddUint32(&value, 1)
ch <- struct{}{}
})
r1 := atomic.LoadUint32(&value)
fmt.Println(r1)
<-ch
if timer.Stop() {
<-timer.C
}
r1 = atomic.LoadUint32(&value)
fmt.Println(r1)
after := time.Since(now).Milliseconds()
fmt.Println(after)
}0
1
20
func Difference
func Difference[T comparable](s1, s2 []T) []TDifference is similar to Without, but returns the values from the first slice that are not present in the second slice.
func DifferenceBy
func DifferenceBy[T comparable](s1, s2 []T, fn func(T) T) []TDifferenceBy is like Difference, except that invokes a callback function on each element of the slice, applying the criteria by which the difference is computed.
func Drop
func Drop[T any](slice []T, n int) []TDrop creates a new slice with n elements dropped from the beginning. If n < 0 the elements will be dropped from the back of the collection.
func DropWhile
func DropWhile[T any](slice []T, fn func(T) bool) []TDropWhile creates a new slice excluding the elements dropped from the beginning. Elements are dropped by applying the condition invoked in the callback function.
Example
{
res := DropWhile([]string{"a", "aa", "bbb", "ccc"}, func(elem string) bool {
return len(elem) > 2
})
fmt.Println(res)
}[a aa]
func DropRightWhile
func DropRightWhile[T any](slice []T, fn func(T) bool) []TDropRightWhile creates a new slice excluding the elements dropped from the end. Elements are dropped by applying the condition invoked in the callback function.
func Duplicate
func Duplicate[T comparable](slice []T) []TDuplicate returns the duplicated values of a collection.
Example
{
input := []int{-1, -1, 0, 1, 2, 3, 2, 5, 1, 6}
fmt.Println(Duplicate(input))
}[-1 1 2]
func DuplicateWithIndex
func DuplicateWithIndex[T comparable](slice []T) map[T]intDuplicateWithIndex puts the duplicated values of a collection into a map as a key value pair, where the key is the collection element and the value is its position.
Example
{
input := []int{-1, -1, 0, 1, 2, 3, 2, 5, 1, 6}
fmt.Println(DuplicateWithIndex(input))
}map[-1:0 1:3 2:4]
func Equal
func Equal[T comparable](a, b T) boolEqual checks if two values are equal.
func Every
func Every[T any](slice []T, fn func(T) bool) boolEvery returns true if all the elements of a slice satisfies the criteria of the callback function.
func Filter
func Filter[T any](slice []T, fn func(T) bool) []TFilter returns all the elements from the collection which satisfies the conditional logic of the callback function.
Example
{
input := []int{1, 2, 3, 4, 5, 10, 20, 30, 40, 50}
res := Filter(input, func(val int) bool {
return val >= 10
})
fmt.Println(res)
}[10 20 30 40 50]
func Filter2DMapCollection[K comparable, V any](collection []map[K]map[K]V, fn func(map[K]V) bool) []map[K]map[K]VFilter2DMapCollection filter out a two-dimensional collection of map items by applying the conditional logic of the callback function.
func FilterMap
func FilterMap[K comparable, V any](m map[K]V, fn func(V) bool) map[K]VFilterMap iterates over the elements of a collection and returns a new collection representing all the items which satisfies the criteria formulated in the callback function.
Example
{
input := map[int]string{1: "John", 2: "Doe", 3: "Fred"}
res := FilterMap(input, func(v string) bool {
return v == "John"
})
fmt.Println(res)
}map[1:John]
func FilterMapCollection
func FilterMapCollection[K comparable, V any](collection []map[K]V, fn func(V) bool) []map[K]VFilterMapCollection filter out a one dimensional collection of map items by applying the conditional logic of the callback function.
Example
{
input := []map[string]int{
{"bernie": 22},
{"robert": 30},
}
res := FilterMapCollection(input, func(val int) bool {
return val > 22
})
fmt.Println(res)
}[map[robert:30]]
func Find
func Find[K constraints.Ordered, V any](m map[K]V, fn func(V) bool) map[K]VFind iterates over the elements of a map and returns the first item for which the callback function returns true.
func FindAll
func FindAll[T any](s []T, fn func(T) bool) map[int]TFindAll is like FindIndex, but returns into a map all the values which satisfies the conditional logic of the callback function. The map key represents the position of the found value and the value is the item itself.
Example
{
input := []int{1, 2, 3, 4, 2, -2, -1, 2}
items := FindAll(input, func(v int) bool {
return v == 2
})
fmt.Println(items)
}map[1:2 4:2 7:2]
func FindByKey
func FindByKey[K comparable, V any](m map[K]V, fn func(K) bool) map[K]VFindByKey is like Find, but returns the first item for which the callback function returns true.
func FindIndex
func FindIndex[T any](s []T, fn func(T) bool) intFindIndex returns the index of the first found element.
func FindKey
func FindKey[K comparable, V any](m map[K]V, fn func(V) bool) KFindKey is like Find, but returns the first item key position for which the callback function returns true.
func FindLastIndex
func FindLastIndex[T any](s []T, fn func(T) bool) intFindLastIndex is like FindIndex, only that returns the index of last found element.
func FindMax
func FindMax[T constraints.Ordered](s []T) TFindMax finds the maximum value of a slice.
func FindMaxBy
func FindMaxBy[T constraints.Ordered](s []T, fn func(val T) T) TFindMaxBy is like FindMax except that it accept a callback function and the conditional logic is applied over the resulted value. If there are more than one identical values resulted from the callback function the first one is returned.
func FindMaxByKey
func FindMaxByKey[K comparable, T constraints.Ordered](mapSlice []map[K]T, key K) (T, error)FindMaxByKey finds the maximum value from a map by using some existing key as a parameter.
func FindMin
func FindMin[T constraints.Ordered](s []T) TFindMin finds the minimum value of a slice.
func FindMinBy
func FindMinBy[T constraints.Ordered](s []T, fn func(val T) T) TFindMinBy is like FindMin except that it accept a callback function and the conditional logic is applied over the resulted value. If there are more than one identical values resulted from the callback function the first one is used.
func FindMinByKey
func FindMinByKey[K comparable, T constraints.Ordered](mapSlice []map[K]T, key K) (T, error)FindMinByKey finds the minimum value from a map by using some existing key as a parameter.
func Flatten
func Flatten[T any](slice any) ([]T, error)Flatten flattens the slice all the way down to the deepest nesting level.
Example
{
input := []any{[]int{1, 2, 3}, []any{[]int{4}, 5}}
result, _ := Flatten[int](input)
fmt.Println(result)
}[1 2 3 4 5]
func Flip
func Flip[T any](fn func(args ...T) []T) func(args ...T) []TFlip creates a function that invokes fn with arguments reversed.
Example
{
flipped := Flip(func(args ...int) []int {
return ToSlice(args...)
})
fmt.Println(flipped(1, 2, 3))
}[3 2 1]
func ForEach
func ForEach[T any](slice []T, fn func(T))ForEach iterates over the elements of a collection and invokes the callback fn function on each element.
Example
{
input := []int{1, 2, 3, 4}
output := []int{}
ForEach(input, func(val int) {
val = val * 2
output = append(output, val)
})
fmt.Println(output)
}[2 4 6 8]
func ForEachRight
func ForEachRight[T any](slice []T, fn func(T))ForEachRight is the same as ForEach, but starts the iteration from the last element.
func GroupBy
func GroupBy[T1, T2 comparable](slice []T1, fn func(T1) T2) map[T2][]T1GroupBy splits a collection into a key-value set, grouped by the result of running each value through the callback function fn. The return value is a map where the key is the conditional logic of the callback function and the values are the callback function returned values.
Example
{
input := []float64{1.3, 1.5, 2.1, 2.9}
res := GroupBy(input, func(val float64) float64 {
return math.Floor(val)
})
fmt.Println(res)
}map[1:[1.3 1.5] 2:[2.1 2.9]]
func InRange
func InRange[T Number](num, lo, up T) boolInRange checks if a number is inside a range.
func IndexOf
func IndexOf[T comparable](s []T, val T) intIndexOf returns the index of the firs occurrence of a value in the slice, or -1 if value is not present in the slice.
func Intersection
func Intersection[T comparable](params ...[]T) []TIntersection computes the list of values that are the intersection of all the slices. Each value in the result should be present in each of the provided slices.
Example
{
res1 := Intersection([]int{1, 2, 4}, []int{0, 2, 1}, []int{2, 1, -2})
fmt.Println(res1)
res2 := Intersection([]string{"a", "b"}, []string{"a", "a", "a"}, []string{"b", "a", "e"})
fmt.Println(res2)
}[1 2]
[a]
func IntersectionBy
func IntersectionBy[T comparable](fn func(T) T, params ...[]T) []TIntersectionBy is like Intersection, except that it accepts and callback function which is invoked on each element of the collection.
Example
{
result1 := IntersectionBy(func(v float64) float64 {
return math.Floor(v)
}, []float64{2.1, 1.2}, []float64{2.3, 3.4}, []float64{1.0, 2.3})
fmt.Println(result1)
result2 := IntersectionBy(func(v int) int {
return v % 2
}, []int{1, 2}, []int{2, 1})
fmt.Println(result2)
}[2.1]
[1 2]
func Invert
func Invert[K, V comparable](m map[K]V) map[V]KInvert returns a copy of the map where the keys become the values and the values the keys. For this to work, all of your map's values should be unique.
func KebabCase
func KebabCase[T ~string](str T) TKebabCase converts a string to kebab-case (https://en.wikipedia.org/wiki/Letter_case#Kebab_case\).
Example
{
fmt.Println(KebabCase("fooBarBaz"))
fmt.Println(KebabCase("Foo BarBaz"))
fmt.Println(KebabCase("Foo_Bar_Baz"))
}foo-bar-baz
foo-bar-baz
foo-bar-baz
func Keys[K comparable, V any](m map[K]V) []KKeys retrieve all the existing keys of a map.
func LastIndexOf
func LastIndexOf[T comparable](s []T, val T) intLastIndexOf returns the index of the last occurrence of a value.
func Less
func Less[T constraints.Ordered](a, b T) boolLess checks if the first value is less than the second.
func Map
func Map[T1, T2 any](slice []T1, fn func(T1) T2) []T2Map produces a new slice of values by mapping each value in the list through a transformation function.
Example
{
res := Map([]int{1, 2, 3}, func(val int) int {
return val * 2
})
fmt.Println()
}[2 4 6]
func MapCollection
func MapCollection[K comparable, V any](m map[K]V, fn func(V) V) []VMapCollection is like the Map method, but applied to maps. It runs each element of the map over an iteratee function and saves the resulted values into a new map.
func MapContains
func MapContains[K, V comparable](m map[K]V, value V) boolMapContains returns true if the value is present in the list otherwise false.
func MapEvery
func MapEvery[K comparable, V any](m map[K]V, fn func(V) bool) boolMapEvery returns true if all the elements of a map satisfies the criteria of the callback function.
func MapKeys
func MapKeys[K comparable, V any, R comparable](m map[K]V, fn func(K, V) R) map[R]VMapKeys is the opposite of MapValues. It creates a new map with the same number of elements as the original one, but this time the callback function (fn) is invoked over the map keys.
func MapSome
func MapSome[K comparable, V any](m map[K]V, fn func(V) bool) boolMapSome returns true if some elements of a map satisfies the criteria of the callback function.
func MapUnique
func MapUnique[K, V comparable](m map[K]V) map[K]VMapUnique removes the duplicate values from a map.
func MapValues
func MapValues[K comparable, V, R any](m map[K]V, fn func(V) R) map[K]RMapValues creates a new map with the same number of elements as the original one, but running each map value through a callback function (fn).
func Max
func Max[T constraints.Ordered](values ...T) TMax returns the biggest value from the provided parameters.
func Mean
func Mean[T Number](slice []T) TMean computes the mean value of the slice elements.
func Merge
func Merge[T any](s []T, params ...[]T) []TMerge merges the first slice with the other slices defined as variadic parameter.
func Min
func Min[T constraints.Ordered](values ...T) TMin returns the lowest value from the provided parameters.
func N
func N[T Number](s string) (T, error)N converts a string to a generic number.
func NewDebounce
func NewDebounce(wait time.Duration) (func(f func()), func())NewDebounce creates a new debounced version of the invoked function which postpone the execution with a time delay passed in as a function argument. It returns a callback function which will be invoked after the predefined delay and also a cancel method which should be invoked to cancel a scheduled debounce.
Example
{
var (
counter1 uint64
counter2 uint64
)
f1 := func() {
atomic.AddUint64(&counter1, 1)
}
f2 := func() {
atomic.AddUint64(&counter2, 1)
}
debounce, cancel := NewDebounce(10 * time.Millisecond)
for i := 0; i < 2; i++ {
for j := 0; j < 100; j++ {
debounce(f1)
}
<-time.After(20 * time.Millisecond)
}
cancel()
debounce, cancel = NewDebounce(10 * time.Millisecond)
for i := 0; i < 5; i++ {
for j := 0; j < 50; j++ {
debounce(f2)
}
for j := 0; j < 50; j++ {
debounce(f2)
}
<-time.After(20 * time.Millisecond)
}
cancel()
c1 := atomic.LoadUint64(&counter1)
c2 := atomic.LoadUint64(&counter2)
fmt.Println(c1)
fmt.Println(c2)
}2
5
func Nth
func Nth[T any](slice []T, nth int) (T, error)Nth returns the nth element of the collection. In case of negative value the nth element is returned from the end of the collection. In case nth is out of bounds an error is returned.
func Null
func Null[T any]() Tfunc NumToString
func NumToString[T Number](n T) stringNumToString converts a number to a string. In case of a number of type float (float32|float64) this will be rounded to 2 decimal places.
func Omit
func Omit[K comparable, V any](collection map[K]V, keys ...K) map[K]VOmit is the opposite of Pick, it extracts all the map elements which keys are not omitted.
Example
{
res := Omit(map[string]any{"name": "moe", "age": 40, "active": false}, "name", "age")
fmt.Println(res)
}map[active:false]
func OmitBy
func OmitBy[K comparable, V any](collection map[K]V, fn func(key K, val V) bool) map[K]VOmitBy is the opposite of PickBy, it removes all the map elements for which the callback function returns true.
Example
{
res := OmitBy(map[string]int{"a": 1, "b": 2, "c": 3}, func(key string, val int) bool {
return val%2 == 1
})
fmt.Println(res)
}map[b:2]
func Once
func Once[S ~string, T comparable, V constraints.Signed](c *cache.Cache[S, T], fn func() T) TOnce is like Before, but it's invoked only once. Repeated calls to the modified function will have no effect and the function invocation is returned from the cache.
Example
{
c := cache.New[string, int](cache.DefaultExpiration, cache.NoExpiration)
ForEach([]int{1, 2, 3, 4, 5}, func(val int) {
fn := func(val int) func() int {
<-time.After(10 * time.Millisecond)
return func() int {
return val
}
}
res := Once[string, int, int](c, fn(val))
// We can test the implementation correctness by invoking the `Once` function multiple times.
// When it's invoked for the first time the result should be served from the callback function.
// From the second invocation onward the results are served from the cache.
// In our example the results of each invokation should be always equal with 1.
fmt.Println(res)
})
c.Flush()
}1
1
1
1
1
func Pad
func Pad[T ~string](str T, size int, token string) TPad pads string on the left and right sides if it's shorter than length. Padding characters are truncated if they can't be evenly divided by length.
Example
{
fmt.Println(Pad("abc", 2, "."))
fmt.Println(Pad("abc", 3, "."))
fmt.Println(Pad("abc", 4, "."))
fmt.Println(Pad("abc", 5, "."))
}abc
abc
abc.
.abc.
func PadLeft
func PadLeft[T ~string](str T, size int, token string) TPadLeft pads string on the left side if it's shorter than length. Padding characters are truncated if they exceed length.
Example
{
fmt.Println(PadLeft("abc", 8, "..."))
fmt.Println(PadLeft("abc", 4, "_"))
fmt.Println(PadLeft("abc", 6, "_-"))
}.....abc
_abc
_-_abc
func PadRight
func PadRight[T ~string](str T, size int, token string) TPadRight pads string on the right side if it's shorter than length. Padding characters are truncated if they exceed length.
Example
{
fmt.Println(PadRight("abc", 8, "..."))
fmt.Println(PadRight("abc", 6, "........"))
}abc.....
abc...
func Partition
func Partition[T comparable](slice []T, fn func(T) bool) [2][]TPartition splits the collection elements into two, the ones which satisfies the condition expressed in the callback function (fn) and those which does not satisfy the condition.
Example
{
input := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
res1 := Partition(input, func(val int) bool {
return val >= 5
})
fmt.Println(res1)
res2 := Partition(input, func(val int) bool {
return val < 5
})
fmt.Println(res2)
}[[5 6 7 8 9] [0 1 2 3 4]]
[[0 1 2 3 4] [5 6 7 8 9]]
func PartitionMap
func PartitionMap[K comparable, V any](mapSlice []map[K]V, fn func(map[K]V) bool) [2][]map[K]VPartitionMap split the collection into two arrays, the one whose elements satisfy the condition expressed in the callback function (fn) and one whose elements don't satisfy the condition.
func Pick
func Pick[K comparable, V any](collection map[K]V, keys ...K) (map[K]V, error)Pick extracts the elements from the map which have the key defined in the allowed keys.
Example
{
res, _ := Pick(map[string]any{"name": "moe", "age": 20, "active": true}, "name", "age")
fmt.Println(res)
}map[age:20 name:moe]
func PickBy
func PickBy[K comparable, V any](collection map[K]V, fn func(key K, val V) bool) map[K]VPickBy extracts all the map elements for which the callback function returns truthy.
Example
{
res := PickBy(map[string]int{"aa": 1, "b": 2, "c": 3}, func(key string, val int) bool {
return len(key) == 1
})
fmt.Println(res)
}map[b:2 c:3]
func Pluck
func Pluck[K comparable, V any](mapSlice []map[K]V, key K) []VPluck extracts all the values of a map by the key definition.
Example
{
input := []map[string]string{
{"name": "moe", "email": "moe@example.com"},
{"name": "larry", "email": "larry@example.com"},
{"name": "curly", "email": "curly@example.com"},
{"name": "moly", "email": "moly@example.com"},
}
res := Pluck(input, "name")
fmt.Println(res)
}[moe larry curly moly]
func Range
func Range[T Number](args ...T) ([]T, error)Range creates a slice of integers progressing from start up to, but not including end. This method can accept 1, 2 or 3 arguments. Depending on the number of provided parameters, `start`, `step` and `end` has the following meaning:
[start=0]: The start of the range. If omitted it defaults to 0.
[step=1]: The value to increment or decrement by.
end: The end of the range.
In case you'd like negative values, use a negative step.
Example
{
r1, _ := Range(5)
r2, _ := Range(1, 5)
r3, _ := Range(0, 2, 10)
r4, _ := Range(-4)
r5, _ := Range(-1, -4)
r6, _ := Range(0, -1, -4)
r7, _ := Range[float64](0, 0.12, 0.9)
fmt.Println(r1)
fmt.Println(r2)
fmt.Println(r3)
fmt.Println(r4)
fmt.Println(r5)
fmt.Println(r6)
fmt.Println(r7)
}[0 1 2 3 4]
[1 2 3 4]
[0 2 4 6 8]
[0 -1 -2 -3]
[-1 -2 -3]
[0 -1 -2 -3]
[0 0.12 0.24 0.36 0.48 0.6 0.72 0.84]
func RangeRight
func RangeRight[T Number](params ...T) ([]T, error)RangeRight is like Range, only that it populates the slice in descending order.
func Reduce
func Reduce[T1, T2 any](slice []T1, fn func(T1, T2) T2, initVal T2) T2Reduce reduces the collection to a value which is the accumulated result of running each element in the collection through the callback function yielding a single value.
Example
{
input1 := []int{1, 2, 3, 4}
res1 := Reduce(input1, func(a, b int) int {
return a + b
}, 0)
fmt.Println(res1)
input2 := []string{"a", "b", "c", "d"}
res2 := Reduce(input2, func(a, b string) string {
return b + a
}, "")
fmt.Println(res2)
}10
abcd
func Reject
func Reject[T any](slice []T, fn func(val T) bool) []TReject is the opposite of Filter. It returns the values from the collection without the elements for which the callback function returns true.
Example
{
input := []int{1, 2, 3, 4, 5, 6, 10, 20, 30, 40, 50}
res = Reject(input, func(val int) bool {
return val >= 10
})
fmt.Println(res)
}[1 2 3 4 5 6]
func Reverse
func Reverse[T any](sl []T) []TReverse reverses the order of elements, so that the first element becomes the last, the second element becomes the second to last, and so on.
func ReverseStr
func ReverseStr[T ~string](str T) TReverseStr returns a new string with the characters in reverse order.
func Shuffle
func Shuffle[T any](src []T) []TShuffle implements the Fisher-Yates shuffle algorithm applied to a slice.
func SliceToMap
func SliceToMap[K comparable, T any](s1 []K, s2 []T) map[K]TSliceToMap converts a slice to a map. It panics in case the parameter slices length are not identical. The map keys will be the items from the first slice and the values the items from the second slice.
func SnakeCase
func SnakeCase[T ~string](str T) TSnakeCase converts a string to snake_case (https://en.wikipedia.org/wiki/Snake_case\).
Example
{
fmt.Println(SnakeCase("fooBarBaz"))
fmt.Println(SnakeCase("Foo BarBaz"))
fmt.Println(SnakeCase("Foo_Bar_Baz"))
}foo_bar_baz
foo_bar_baz
foo_bar_baz
func Some
func Some[T any](slice []T, fn func(T) bool) boolSome returns true if some elements of a slice satisfies the criteria of the callback function.
func SplitAtIndex
func SplitAtIndex[T ~string](str T, index int) []TSplitAtIndex split the string at the specified index and returns a slice with the resulted two substrings.
Example
{
fmt.Println(SplitAtIndex("abcdef", -1))
fmt.Println(SplitAtIndex("abcdef", 0))
fmt.Println(SplitAtIndex("abcdef", 1))
fmt.Println(SplitAtIndex("abcdef", 2))
fmt.Println(SplitAtIndex("abcdef", 5))
fmt.Println(SplitAtIndex("abcdef", 6))
}[ abcdef]
[a bcdef]
[ab cdef]
[abc def]
[abcdef ]
[abcdef ]
func Substr
func Substr[T ~string](str T, offset, length int) TSubstr returns the portion of string specified by the offset and length.
If offset is non-negative, the returned string will start at the offset'th position in string, counting from zero.
If offset is negative, the returned string will start at the offset'th character from the end of string.
If string is less than offset characters long, an empty string will be returned.
If length is negative, then that many characters will be omitted from the end of string starting from the offset position.
Example
{
str1 := Substr("abcdef", 0, 0)
str2 := Substr("abcdef", -1, 0)
str3 := Substr("abcdef", 7, 7)
str4 := Substr("abcdef", 0, 20)
str5 := Substr("abcdef", 5, 10)
str6 := Substr("abcdef", 0, -1)
str7 := Substr("abcdef", 2, -1)
str8 := Substr("abcdef", 4, -4)
str9 := Substr("abcdef", -3, -1)
str10 := Substr("abcdef", 1, 3)
fmt.Println(str1)
fmt.Println(str2)
fmt.Println(str3)
fmt.Println(str4)
fmt.Println(str5)
fmt.Println(str6)
fmt.Println(str7)
fmt.Println(str8)
fmt.Println(str9)
fmt.Println(str10)
}abcdef
f
abcde
cde
de
bcd
func Sum
func Sum[T Number](slice []T) TSum returns the sum of the slice items. These have to satisfy the type constraints declared as Number.
func SumBy
func SumBy[T1 any, T2 Number](slice []T1, fn func(T1) T2) T2SumBy is like Sum except it accept a callback function which is invoked for each element in the slice to generate the value to be summed.
func ToLower
func ToLower[T ~string](str T) TToLower converts a string to Lowercase.
func ToSlice
func ToSlice[T any](args ...T) []TToSlice returns the function arguments as a slice.
func ToUpper
func ToUpper[T ~string](str T) TToUpper converts a string to Uppercase.
func Union[T comparable](slice any) ([]T, error)Union computes the union of the passed\-in slice and returns an ordered list of unique items that are present in one or more of the slices.
Example
{
input := []any{[]any{1, 2, []any{3, []int{4, 5, 6}}}, 7, []int{1, 2}, 3, []int{4, 7}, 8, 9, 9}
res, _ := Union[int](input)
fmt.Println(res)
}[1 2 3 4 5 6 7 8 9]
func Unique
func Unique[T comparable](slice []T) []TUnique returns the collection unique values.
func UniqueBy
func UniqueBy[T comparable](slice []T, fn func(T) T) []TUniqueBy is like Unique except that it accept a callback function which is invoked on each element of the slice applying the criteria by which the uniqueness is computed.
func Unwrap
func Unwrap[T ~string](str T, token string) TUnwrap a string with the specified token.
Example
{
fmt.Println(Unwrap("'abc'", "'"))
fmt.Println(Unwrap("*abc*", "*"))
fmt.Println(Unwrap("*a*bc*", "*"))
fmt.Println(Unwrap("''abc''", "''"))
fmt.Println(Unwrap("\"abc\"", "\""))
}abc
abc
a*bc
abc
abc
func Unzip
func Unzip[T any](slices ...[]T) [][]TUnzip is the opposite of Zip: given a slice of slices it returns a series of new slices, the first of which contains all the first elements in the input slices, the second of which contains all the second elements, and so on.
Example
{
res := Unzip([]any{"one", 1}, []any{"two", 2})
fmt.Println(res)
}[[one two] [1 2]]
func Values
func Values[K comparable, V any](m map[K]V) []VValues retrieve all the existing values of a map.
func Without
func Without[T1 comparable, T2 any](slice []T1, values ...T1) []T1Without returns a copy of the slice with all the values defined in the variadic parameter removed.
Example
{
fmt.Println(Without[int, int]([]int{2, 1, 2, 3}, 1, 2))
fmt.Println(Without[int, int]([]int{1, 2, 3, 4}, 3, 4))
fmt.Println(Without[int, int]([]int{0, 1, 2, 3, 4, 5}, 0, 3, 4, 5))
fmt.Println(Without[float64, float64]([]float64{1.0, 2.2, 3.0, 4.2}, 3.0, 4.2))
}[3]
[1 2]
[1 2]
[1 2.2]
func Wrap
func Wrap[T ~string](str T, token string) TWrap a string with the specified token.
Example
{
fmt.Println(Unwrap("'abc'", "'"))
fmt.Println(Unwrap("*abc*", "*"))
fmt.Println(Unwrap("*a*bc*", "*"))
fmt.Println(Unwrap("''abc''", "''"))
fmt.Println(Unwrap("\"abc\"", "\""))
}abc
abc
a*bc
abc
abc
func WrapAllRune
func WrapAllRune[T ~string](str T, token string) TWrapAllRune is like Wrap, only that it's applied over runes instead of strings.
Example
{
fmt.Println(WrapAllRune("abc", ""))
fmt.Println(WrapAllRune("abc", "'"))
fmt.Println(WrapAllRune("abc", "*"))
fmt.Println(WrapAllRune("abc", "-"))
}abc
'a''b''c'
*a**b**c*
-a--b--c-
func Zip
func Zip[T any](slices ...[]T) [][]TZip iteratively merges together the values of the slice parameters with the values at the corresponding position.
type Bound
type Bound[T constraints.Signed] struct {
Min, Max T
}func (Bound[T]) Enclose
func (b Bound[T]) Enclose(nth T) boolEnclose checks if an element is inside the bounds.
type CompFn
CompFn is a generic function type for comparing two values.
type CompFn[T any] func(a, b T) boolfunc NewMemoizer
func NewMemoizer[T ~string, V any](expiration, cleanup time.Duration) *Memoizer[T, V]NewMemoizer instantiates a new Memoizer.
func (Memoizer[T, V]) Memoize
func (m Memoizer[T, V]) Memoize(key T, fn func() (*cache.Item[V], error)) (*cache.Item[V], error)Memoize returns the item under a specific key instantly in case the key exists, otherwise returns the results of the given function, making sure that only one execution is in-flight for a given key at a time.
This method is useful for caching the result of a time-consuming operation when is more important to return a slightly outdated result, than to wait for an operation to complete before serving it.
Example
{
m := NewMemoizer[string, any](time.Second, time.Minute)
sampleItem := map[string]any{
"foo": "one",
"bar": "two",
"baz": "three",
}
expensiveOp := func() (*cache.Item[any], error) {
// Here we are simulating an expensive operation.
time.Sleep(500 * time.Millisecond)
foo := FindByKey(sampleItem, func(key string) bool {
return key == "foo"
})
m.Cache.MapToCache(foo, cache.DefaultExpiration)
item, err := m.Cache.Get("foo")
if err != nil {
return nil, err
}
return item, nil
}
fmt.Println(m.Cache.List())
// Caching the result of some expensive fictive operation result.
data, _ := m.Memoize("key1", expensiveOp)
fmt.Println(len(m.Cache.List()))
item, _ := m.Cache.Get("key1")
fmt.Println(item.Val())
// Serving the expensive operation result from the cache. This should return instantly.
// If it would invoked the expensiveOp function this would be introduced a 500 millisecond latency.
data, _ = m.Memoize("key1", expensiveOp)
fmt.Println(data.Val())
}map[]
2
one
one
type Number
Number is a custom type set of constraints extending the Float and Integer type set from the experimental constraints package.
type Number interface {
// contains filtered or unexported methods
}type RType
RType is a generic struct type used as method receiver on retry operations.
type RType[T any] struct {
Input T
}func (RType[T]) Retry
func (v RType[T]) Retry(n int, fn func(T) error) (int, error)Retry tries to invoke the callback function `n` times. It runs until the number of attempts is reached or the returned value of the callback function is nil.
Example
{
n := 2
idx := 0
ForEach([]string{"one", "two", "three"}, func(val string) {
rt := RType[string]{Input: val}
attempts, e := rt.Retry(n, func(elem string) (err error) {
if len(elem)%3 != 0 {
err = fmt.Errorf("retry failed: number of %d attempts exceeded", n)
}
return err
})
switch idx {
case 0:
fmt.Println(attempts)
case 1:
fmt.Println(attempts)
case 2:
fmt.Println(attempts)
fmt.Println(e)
}
idx++
})
}0
0
2
retry failed: number of 2 attempts exceeded
func (RType[T]) RetryWithDelay
func (v RType[T]) RetryWithDelay(n int, delay time.Duration, fn func(time.Duration, T) error) (time.Duration, int, error)RetryWithDelay tries to invoke the callback function `n` times, but with a delay between each call. It runs until the number of attempts is reached or the error return value of the callback function is nil.
Example
{
n := 5
// In this example we are simulating an external service. In case the response time
// exceeds a certain time limit we stop retrying and we are returning an error.
services := []struct {
service string
time time.Duration
}{
{service: "AWS1"},
{service: "AWS2"},
}
type Service[T ~string] struct {
Service T
Time time.Duration
}
for _, srv := range services {
r := random(1, 10)
// Here we are simulating the response time of the external service
// by generating some random duration between 1ms and 10ms.
// All the test should pass because all of the responses are inside the predefined limit (10ms).
service := Service[string]{
Service: srv.service,
Time: time.Duration(r) * time.Millisecond,
}
rtyp := RType[Service[string]]{
Input: service,
}
d, att, e := rtyp.RetryWithDelay(n, 20*time.Millisecond, func(d time.Duration, srv Service[string]) (err error) {
if srv.Time.Milliseconds() > 10 {
err = fmt.Errorf("retry failed: service time exceeded")
}
return err
})
fmt.Println(e)
fmt.Println(att)
fmt.Println(d.Milliseconds())
}
}<nil>
0
0
- Request new features or fix open issues
- Fork the project and make pull requests
- Endre Simo (@simo_endre)
Copyright © 2022 Endre Simo
This software is distributed under the MIT license. See the LICENSE file for the full license text.
