Lo Learn Examples

Demo for slices: demos for filter

Iterates over a collection and returns an array of all the elements the predicate function returns true for.

Running example:
Result:
Even numbers:[2 4 6 8 10]
Odd numbers:[1 3 5 7 9]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/filter.go:34

Demo for slices: demos for map

Manipulates a slice of one type and transforms it into a slice of another type

Running example:
Result:
[2 4 6 8]
[1x2=2 2x2=4 3x2=6 4x2=8]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/map.go:31

Demo for slices: demos for filter_map

Returns a slice which obtained after both filtering and mapping using the given callback function. The callback function should return two values: the result of the mapping operation and whether the result element should be included or not.

Running example:
Result:
[4 8]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/filter_map.go:28

Demo for slices: demos for flat_slice

Manipulates a slice and transforms and flattens it to a slice of another type. The transform function can either return a slice or a nil, and in the nil case no value is added to the final slice.

Running example:
Result:
[11 3 3 3 110 6 6 6 1001 11 9 9 1100 14 12 c]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/flat_slice.go:32

Demo for slices: demos for reduce

Reduces a collection to a single value. The value is calculated by accumulating the result of running each element in the collection through an accumulator function. Each successive invocation is supplied with the return value returned by the previous call.

Running example:
Result:
10
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/reduce.go:27

Demo for slices: demos for reduce_right

Like lo.Reduce except that it iterates over elements of collection from right to left.

Running example:
Result:
[10086 8848 7 8 9 4 5 6 1 2 3]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/reduce_right.go:31

Demo for slices: demos for for_each

Iterates over a collection and applies a function to each element.

Running example:
index: 0, value: 1
index: 1, value: 2
index: 2, value: 3
index: 3, value: 4
index: 4, value: 5
index: 5, value: 6
index: 6, value: 7
index: 7, value: 8
index: 8, value: 9
index: 9, value: 10
Result:
Sequential execution
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/for_each.go:29

Demo for slices: demos for for_each_parallel

Like lo.ForEach except that it runs the iteratee function in parallel.

Running example:
index: 9, value: 10
index: 4, value: 5
index: 5, value: 6
index: 8, value: 9
index: 3, value: 4
index: 0, value: 1
index: 1, value: 2
index: 2, value: 3
index: 7, value: 8
index: 6, value: 7
Result:
Parallel execution
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/for_each.go:51

Demo for slices: demos for for_each_while

Iterates over a collection and applies a function to each element. The iteratee function can return false to break the loop.

Running example:
index: 0, value: 1
index: 1, value: 2
index: 2, value: 3
index: 3, value: 4
index: 4, value: 5
Result:
Sequential execution
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/for_each.go:74

Demo for slices: demos for times

Times invokes the iteratee n times, returning an array of the results of each invocation. The iteratee is invoked with index as argument.

Running example:
Result:
403.7915ms
[banana bananana banananana bananananana banananananana]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/times.go:30

Demo for slices: demos for times_parallel

Like lo.Times except that it runs the iteratee function in parallel.

Running example:
Result:
101.099834ms
[banana bananana banananana bananananana banananananana]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/times.go:55

Demo for slices: demos for uniq

Creates a duplicate-free version of an array.

Running example:
Result:
[1 2 3 4 5 6 7 8 9 10]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/uniq.go:23

Demo for slices: demos for uniq_by

Creates a duplicate-free version of an array, using a function to determine uniqueness.

Running example:
Result:
[1 2]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/uniq.go:43

Demo for slices: demos for group_by

Groups the elements of a collection based on the given function.

Running example:
Result:
map[0:[3 6 9] 1:[1 4 7 10] 2:[2 5 8]]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/group_by.go:27

Demo for slices: demos for chunk

Creates an array of elements split into groups the length of size.

Running example:
Result:
[[1 2 3] [4 5 6] [7 8 9] [10]]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/chunk.go:25

Demo for slices: demos for partition_by

Returns an array of elements split into groups. The order of grouped values is determined by the order they occur in collection. The grouping is generated from the results of running each element of collection through iteratee.

Running example:
Result:
[[-2 -1] [1 3 5 7 9] [2 4 6 8 10]]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/partition_by.go:34

Demo for slices: demos for partition_parallel

Like lo.PartitionBy except that it runs the iteratee function in parallel.

Running example:
Result:
[[10 2 4 6 8] [-2 -1] [1 3 5 7 9]]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/partition_by.go:62

Demo for slices: demos for flatten

Returns an array a single level deep.

Running example:
Result:
[1 2 3 4]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/flatten.go:23

Demo for slices: demos for interleave

Round-robin alternating input slices and sequentially appending value at index into result.

Running example:
Result:
[a 1 x b 2 z c 3 4 5]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/interleave.go:25

Demo for slices: demos for shuffle

Returns an array of shuffled values. Uses the Fisher-Yates shuffle algorithm.

Running example:
Result:
[2 5 10 9 6 4 1 7 3 8]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/shuffle.go:21

Demo for slices: demos for reverse

Reverses a slice.This helper is mutable. This behavior might change in v2.0.0.

Running example:
Result:
[5 4 3 2 1]
[5 4 3 2 1]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/reverse.go:21

Demo for slices: demos for fill

Fills elements of slice with value.

Running example:
Result:
[[-1 -1 -1] [-1 -1 -1] [-1 -1 -1]]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/fill.go:28

Demo for slices: demos for repeat

Creates a slice with n values of v.

Running example:
Result:
[[1 2 3] [1 2 3]]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/repeat.go:21

Demo for slices: demos for repeat_by

Builds a slice with values returned by N calls of callback.

Running example:
Result:
[0 1 4]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/repeat_by.go:24

Demo for slices: demos for key_by

Transforms a slice or an array of structs to a map based on a pivot callback.

Running example:
Result:
map[001:{001 Alice 20} 002:{002 Alice 20} 003:{003 Bob 21} 004:{004 Charlie 22} 005:{005 David 23}]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/key_by.go:37

Demo for slices: demos for associate

Returns a map containing key-value pairs provided by transform function applied to elements of the given slice. If any of two pairs would have the same key the last one gets added to the map.

Running example:
Result:
map[001:Alice is 20 years old 002:Alice is 20 years old 003:Bob is 21 years old 004:Charlie is 22 years old 005:David is 23 years old]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/associate.go:32

Demo for slices: demos for drop

Removes n elements from the beginning of slice.

Running example:
Result:
[1 2 3 4 5]
[3 4 5]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/drop.go:21

Demo for slices: demos for dropRight

Removes n elements from the end of slice.

Running example:
Result:
[1 2 3 4 5]
[1 2 3]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/drop.go:37

Demo for slices: demos for dropWhile

Removes elements from slice until predicate returns false.

Running example:
Result:
[1 2 3 2 1]
[3 2 1]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/drop.go:55

Demo for slices: demos for dropRightWhile

Removes elements from slice until predicate returns false.

Running example:
Result:
[1 2 3 2 1]
[1 2 3]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/drop.go:73

Demo for slices: demos for dropByIndex

Drops elements from a slice or array by the index. A negative index will drop elements from the end of the slice.

Running example:
Result:
[0 1 2 3 4 5]
[0 2 4]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/drop.go:89

Demo for slices: demos for reject

Rejects elements of slice with predicate.

Running example:
Result:
[1 2 3 4 5]
[1 3 5]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/reject.go:24

Demo for slices: demos for rejectMap

Rejects elements of slice with predicate and maps the result.

Running example:
Result:
[1 2 3 4 5]
[ood:1 ood:3 ood:5]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/reject.go:42

Demo for slices: demos for filterReject

Mixes Filter and Reject, this method returns two slices, one for the elements of collection that predicate returns truthy for and one for the elements that predicate does not return truthy for.

Running example:
Result:
[2 4]
[1 3 5]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/reject.go:60

Demo for slices: demos for count

Counts the number of elements in the collection that compare equal to value.

Running example:
Result:
2
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/count.go:21

Demo for slices: demos for countBy

Counts the number of elements in the collection that predicate returns truthy for.

Running example:
Result:
2
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/count.go:39

Demo for slices: demos for countValues

Counts the number of each element in the collection.

Running example:
Result:
map[a:3 b:2 c:1 d:3]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/count.go:55

Demo for slices: demos for countValuesBy

Counts the number of each element in the collection. It ss equivalent to chaining lo.Map and lo.CountValues.

Running example:
Result:
map[false:5 true:5]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/count.go:73

Demo for slices: demos for subset

Returns a copy of a slice from offset up to length elements. Like slice[start:start+length], but does not panic on overflow.

Running example:
Result:
[3 4]
[4 5]
[]
[2]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/subset.go:24

Demo for slices: demos for slice

Returns a copy of a slice from start up to end elements. Like slice[start:end], but does not panic on overflow.

Running example:
Result:
[3 4 5]
[4 5]
[]
[1]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/subset.go:45

Demo for slices: demos for replace

Returns a copy of the slice with the first n non-overlapping instances of old replaced by new.

Running example:
Result:
[0 1 1 1 1 1 1 1 1 1]
[0 0 1 1 1 1 1 1 1 1]
[0 0 0 1 1 1 1 1 1 1]
[0 0 0 0 1 1 1 1 1 1]
[0 0 0 0 0 1 1 1 1 1]
[0 0 0 0 0 0 0 0 0 0]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/replace.go:20

Demo for slices: demos for replaceAll

Returns a copy of the slice with all non-overlapping instances of old replaced by new.

Running example:
Result:
[0 0 0 0 0 0 0 0 0 0]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/replace.go:42

Demo for slices: demos for compact

Returns a slice of all non-zero elements.

Running example:
Result:
[1 2 3 4 5]
[a b c]
[true true]
[1 2 3]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/compact.go:19

Demo for slices: demos for isSort

Returns true if the slice is sorted.

Running example:
Result:
true
false
false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/is_sort.go:19

Demo for slices: demos for isSortedByKey

Checks if a slice is sorted by iteratee.

Running example:
Result:
true
false
false
false
true
true
true
false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/is_sort.go:37

Demo for slices: demos for splice

Splice inserts multiple elements at index i. A negative index counts back from the end of the slice. The helper is protected against overflow errors.

Running example:
Result:
[1 2 -1 -2 -3 3 4 5]
[1 2 3 4 -1 -2 -3 5]
[1 2 3 4 5 -1 -2 -3]
[-1 -2 -3 1 2 3 4 5]
[1 2 3 -1 -2 -3 4 5]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/slices/splice.go:20

Demo for maps: demos for keys

Returns a slice of keys in the map.

Running example:
Result:
[c a b]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/keys.go:20

Demo for maps: demos for hasKey

Checks if a key exists in the map.

Running example:
Result:
true
false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/keys.go:37

Demo for maps: demos for values

Returns a slice of values in the map.

Running example:
Result:
[2 3 3 1]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/values.go:20

Demo for maps: demos for valueOr

Returns the value for key in the map. If the key does not exist, it returns the default value.

Running example:
Result:
1
8848
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/values.go:37

Demo for maps: demos for pickBy

Returns same map type filtered by given predicate.

Running example:
Result:
map[b:2 d:4 f:6 h:8 j:10]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/pick_by.go:20

Demo for maps: demos for pickByKeys

Returns same map type filtered by given keys.

Running example:
Result:
map[a:1 b:2 i:9]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/pick_by.go:39

Demo for maps: demos for pickByValues

Returns same map type filtered by given values.

Running example:
Result:
map[a:1 b:2 i:9 j:9]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/pick_by.go:56

Demo for maps: demos for omitBy

Creates an object composed of the properties the given function returns falsey for.

Running example:
Result:
map[a:1 b:2 c:3 d:4 e:5]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/omit_by.go:20

Demo for maps: demos for omitByKeys

Creates an object composed of the properties not in the given keys.

Running example:
Result:
map[c:3 d:4 e:5 f:6 g:7 h:8 j:10]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/omit_by.go:37

Demo for maps: demos for omitByValues

Creates an object composed of the properties not in the given values.

Running example:
Result:
map[c:3 d:4 e:5 f:6 g:7 h:8]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/omit_by.go:54

Demo for maps: demos for entries

Transforms a map into array of key/value pairs.

Running example:
Result:
[{a 1} {b 2} {c 3}]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/entries.go:20

Demo for maps: demos for fromEntries

Transforms an array of key/value pairs into a map.

Running example:
Result:
map[a:1 b:2 c:3]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/entries.go:41

Demo for maps: demos for invert

Creates a map composed of the inverted keys and values. If map contains duplicate values, subsequent values overwrite property assignments of previous values.

Running example:
Result:
map[1:a 2:d 3:c]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/invert.go:20

Demo for maps: demos for assign

Merges multiple maps from left to right.

Running example:
Result:
map[a:1 b:3 c:4 d:5]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/invert.go:39

Demo for maps: demos for mapKeys

Manipulates a map keys and transforms it to a map of another type.

Running example:
Result:
map[A:1 B:2 C:3]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/map.go:21

Demo for maps: demos for mapValues

Manipulates a map values and transforms it to a map of another type.

Running example:
Result:
map[1:A 2:B 3:C]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/map.go:38

Demo for maps: demos for mapEntries

Manipulates a map entries and transforms it to a map of another type.

Running example:
Result:
map[A:a B:b C:c]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/map.go:55

Demo for maps: demos for mapToSlice

Transforms a map into a slice based on specific iteratee.

Running example:
Result:
[a::1 b::2 c::3]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/maps/map.go:74

Demo for math: demos for range/rangeFrom/RangeWithSteps

Creates an array of numbers (positive and/or negative) progressing from start up to, but not including end.

Running example:
Result:
[0 1 2 3 4]
[0 -1 -2 -3 -4]
[2 3 4 5 6]
[5 6]
[1 3]
[5 3]
[1 2 3 4 5]
[1 2 3 4 5]
[1 1.3 1.6 1.9000000000000001 2.2 2.5 2.8 3.0999999999999996 3.3999999999999995 3.6999999999999993 3.999999999999999 4.299999999999999 4.599999999999999 4.899999999999999]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/math/range.go:19

Demo for math: demos for clamp

Clamps number within the inclusive lower and upper bounds.

Running example:
Result:
5
0
10
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/math/clamp.go:19

Demo for math: demos for sum

Calculates the sum of numbers. If collection is empty 0 is returned.

Running example:
Result:
6
0
6.3
6.300000000000001
6
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/math/sum.go:19

Demo for math: demos for mean

Calculates the mean of the numbers.

Running example:
Result:
2
0
2.1000001
2.1
2
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/math/mean.go:19

Demo for math: demos for meanBy

Calculates the mean of the numbers by the given function.

Running example:
Result:
6.6
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/math/mean.go:39

Demo for strings: demos for randomString

Generates a random string of specified length

Running example:
Result:
nnwxx
BCKMI
54246
^.^&*
yxMYeRFSet
EAby7r9u5BfVYW8
&uk0sO+&T;GnHY>"5.4U
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/strings/string.go:19

Demo for strings: demos for substring

Gets the substring of string from the start index up to, but not including, the end index.

Running example:
Result:
Wor
rl
lo, World!
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/strings/string.go:41

Demo for strings: demos for chunkString

Splits string into an array of chunks.

Running example:
Result:
[1 2 3 4 5 6 7 8 9 0]
[12 34 56 78 90]
[123 456 789 0]
[1234 5678 90]
[1234567890]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/strings/string.go:59

Demo for strings: demos for runeLength

Gets the number of characters in string.

Running example:
Result:
13
6
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/strings/string.go:79

Demo for strings: demos for elipse

Truncates string to a specified length.

Running example:
Result:
He...
...
Hello, ...
Hello, World!
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/strings/string.go:96

Demo for strings: demos for PascalCase

Converts a string to PascalCase.

Running example:
Result:
LoLearn
LoLearn
LoLearn
LoLearn
LoLearn
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/strings/word.go:19

Demo for strings: demos for CamelCase

Converts a string to camelCase.

Running example:
Result:
loLearn
loLearn
loLearn
loLearn
loLearn
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/strings/word.go:39

Demo for strings: demos for KebabCase

Converts a string to kebab-case.

Running example:
Result:
lo-learn
lo-learn
lo-learn
lo-learn
lo-learn
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/strings/word.go:59

Demo for strings: demos for SnakeCase

Converts a string to snake_case.

Running example:
Result:
lo_learn
lo_learn
lo_learn
lo_learn
lo_learn
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/strings/word.go:79

Demo for strings: demos for Words

Splits string into an array of its words.

Running example:
Result:
[lo Learn]
[Lo Learn]
[lo learn]
[lo learn]
[lo learn]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/strings/word.go:99

Demo for strings: demos for Capitalize

Converts the first character of string to upper case and the remaining to lower case.

Running example:
Result:
Hello
Hello
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/strings/word.go:119

Demo for tuples: demos for tuple and named tuple 1-9

demos for tuple and named tuple 1-9

Running example:
Result:
{hello 2}
{hello 2 true}
{hello 2 true {bar}}
{hello 2 true {bar} 4.2}
{hello 2 true {bar} 4.2 plop}
{hello 2 true {bar} 4.2 plop false}
{hello 2 true {bar} 4.2 plop false 42}
{hello 2 true {bar} 4.2 plop false 42 hello world}
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/tuples/tuple.go:24

Demo for tuples: demos for unpack

Unpacks a tuple.

Running example:
Result:
hello2
hello2 true
hello2 true {bar}
hello2 true {bar} 4.2
hello2 true {bar} 4.2plop
hello2 true {bar} 4.2plopfalse
hello2 true {bar} 4.2plopfalse 42
hello2 true {bar} 4.2plopfalse 42hello world
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/tuples/tuple.go:47

Demo for tuples: demos for zip

Zip creates a slice of grouped elements, the first of which contains the first elements of the given arrays, the second of which contains the second elements of the given arrays, and so on. When collections have different size, the Tuple attributes are filled with zero value.

Running example:
Result:
[{hello 2} {world 3}]
[{hello 2} {world 3} { 4} { 5}]
[{hello 2}]
[{hello 2 true}]
[{hello 2 true {bar}}]
[{hello 2 true {bar} 4.2}]
[{hello 2 true {bar} 4.2 plop}]
[{hello 2 true {bar} 4.2 plop false}]
[{hello 2 true {bar} 4.2 plop false 42}]
[{hello 2 true {bar} 4.2 plop false 42 hello world}]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/tuples/zip.go:20

Demo for tuples: demos for zipBy

ZipBy creates a slice of grouped elements, the first of which contains the result of applying the given function to the first elements of the given arrays, the second of which contains the result of applying the given function to the second elements of the given arrays, and so on. When collections have different size, the Tuple attributes are filled with zero value.

Running example:
Result:
[hello::2 world::3 !::0]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/tuples/zip.go:46

Demo for tuples: demos for unzip

Unzip converts a slice of grouped elements into a slice of arrays.

Running example:
Result:
[hello world ! plop plop] [2 3 4 5 6]
[hello] [2] [true]
[hello] [2] [true] [{bar}]
[hello] [2] [true] [{bar}] [4.2]
[hello] [2] [true] [{bar}] [4.2] [plop]
[hello] [2] [true] [{bar}] [4.2] [plop] [false]
[hello] [2] [true] [{bar}] [4.2] [plop] [false] [42]
[hello] [2] [true] [{bar}] [4.2] [plop] [false] [42] [hello world]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/tuples/zip.go:74

Demo for tuples: demos for unzipBy

UnzipBy converts a slice of grouped elements into a slice of arrays by applying the given function.

Running example:
Result:
[Alice Bob Charlie]
[1 2 3]
[20 30 40]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/tuples/zip.go:110

Demo for time and duration: demos for duration

Returns the time taken to execute a function.

Running example:
Result:
10.10775ms
11.031083ms
1 11.01275ms
1 2 11.036209ms
1 2 3 10.254208ms
1 2 3 4 11.034875ms
1 2 3 4 5 10.756209ms
1 2 3 4 5 6 10.915625ms
1 2 3 4 5 6 7 11.0425ms
1 2 3 4 5 6 7 8 10.415875ms
1 2 3 4 5 6 7 8 9 11.042666ms
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/duration/duration.go:36

Demo for channels: demos for channel dispatcher

Distributes messages from input channels into N child channels. Close events are propagated to children. Underlying channels can have a fixed buffer capacity or be unbuffered when cap is 0.

Many distributions strategies are available:

  • lo.DispatchingStrategyRoundRobin: Distributes messages in a rotating sequential manner.
  • lo.DispatchingStrategyRandom: Distributes messages in a random manner.
  • lo.DispatchingStrategyWeightedRandom: Distributes messages in a weighted manner.
  • lo.DispatchingStrategyFirst: Distributes messages in the first non-full channel.
  • lo.DispatchingStrategyLeast: Distributes messages in the emptiest channel.
  • lo.DispatchingStrategyMost: Distributes to the fullest channel.

Some strategies bring fallback, in order to favor non-blocking behaviors. See implementations.

For custom strategies, just implement the lo.DispatchingStrategy prototype

Running example:
comsumer 4 gets msg 4
comsumer 0 gets msg 0
comsumer 2 gets msg 2
comsumer 3 gets msg 3
comsumer 1 gets msg 1
comsumer 1 gets msg 6
comsumer 0 gets msg 5
comsumer 4 gets msg 9
comsumer 2 gets msg 7
comsumer 3 gets msg 8
comsumer 3 gets msg 13
comsumer 0 gets msg 10
comsumer 4 gets msg 14
comsumer 2 gets msg 12
comsumer 1 gets msg 11
comsumer 1 gets msg 16
comsumer 4 gets msg 19
comsumer 0 gets msg 15
comsumer 3 gets msg 18
comsumer 2 gets msg 17
closed
closed
closed
closed
closed
Result:
done
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/channels/channel_dispatcher.go:67

Demo for channels: slice to channel

Returns a read-only channels of collection elements. Channel is closed after last element. Channel capacity can be customized.

Running example:
1
2
3
4
5
Result:
done
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/channels/slice_to_channel.go:27

Demo for channels: channel to slice

Collects messages from a channel into a slice. Channel is closed after last element.

Running example:
Result:
[1 2 3 4 5]
[0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/channels/slice_to_channel.go:55

Demo for channels: demo for generator

Implements the generator design pattern. Channel is closed after last element. Channel capacity can be customized.

Running example:
Result:
[0 1 1 2 3 5 8 13 21 34]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/channels/generator.go:32

Demo for channels: demo for buffer

Implements the buffer design pattern. Channel is closed after last element. Channel capacity can be customized.

Running example:
Result:
items: [1 2 3], buffer length=3, read duration is 792ns, channel is open? - true
items: [4 5], buffer length=2, read duration is 375ns, channel is open? - false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/channels/buffer.go:25

Demo for channels: demo for buffer with timeout

Implements the buffer design pattern with timeout. Channel is closed after last element. Channel capacity can be customized.

Running example:
Result:
items: [0 1], buffer length=2, read duration is 101.018125ms, channel is open? - true
items: [2 3 4], buffer length=3, read duration is 78.82575ms, channel is open? - true
items: [], buffer length=0, read duration is 1.542µs, channel is open? - false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/channels/buffer.go:55

Demo for channels: demo for fan in

Merge messages from multiple input channels into a single buffered channel. Output messages has no priority. When all upstream channels reach EOF, downstream channel closes.

Running example:
Result:
[1 1 1 2 2 2 3 3 3 1 1 2 2 3 3]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/channels/fan.go:25

Demo for channels: demo for fan out

Broadcasts all the upstream messages to multiple downstream channels. When upstream channel reach EOF, downstream channels close. If any downstream channels is full, broadcasting is paused.

Running example:
Result:
[1 2 3 4 5]
[1 2 3 4 5]
[1 2 3 4 5]
[1 2 3 4 5]
[1 2 3 4 5]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/channels/fan.go:45

Demo for intersection: demo for contains

Returns true if an element is present in a collection.

Running example:
Result:
true
false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/intersection/contains.go:19

Demo for intersection: demo for contains by

Returns true if the predicate function returns true.

Running example:
Result:
false
true
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/intersection/contains.go:36

Demo for intersection: demo for every

Returns true if all elements of a subset are contained into a collection or if the subset is empty.

Running example:
Result:
true
false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/intersection/every.go:19

Demo for intersection: demo for every by

Returns true if the predicate function returns true for all elements of a subset.

Running example:
Result:
true
false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/intersection/every.go:36

Demo for intersection: demo for some

Returns true if at least one element of a subset is contained into a collection.

Running example:
Result:
false
true
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/intersection/some.go:19

Demo for intersection: demo for some by

Returns true if the predicate function returns true for at least one element of a subset.

Running example:
Result:
true
false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/intersection/some.go:36

Demo for intersection: demo for none

Returns true if none of the elements of a subset are contained into a collection.

Running example:
Result:
true
false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/intersection/none.go:19

Demo for intersection: demo for none by

Returns true if the predicate function returns false for all elements of a subset.

Running example:
Result:
false
true
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/intersection/none.go:36

Demo for intersection: demo for intersect

Returns a new collection containing all elements that are present in all given collections.

Running example:
Result:
[3 4 5]
[]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/intersection/intersect.go:20

Demo for intersection: demo for difference

Returns the difference between two collections.

  • The first value is the collection of element absent of list2.
  • The second value is the collection of element absent of list1.
Running example:
Result:
[1 2] [6]
[1 2 3 4 5] [6 7 8 9]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/intersection/intersect.go:39

Demo for intersection: demo for union

Returns all distinct elements from given collections. Result will not change the order of elements relatively.

Running example:
Result:
[1 2 3 4 5 6 69]
[1 2 3 4 5 6 7 8 9]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/intersection/intersect.go:56

Demo for intersection: demo for without

Returns a collection without the elements of a subset.

Running example:
Result:
[1 2 5]
[1 2 3 4]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/intersection/without.go:19

Demo for intersection: demo for without empty

Deprecated: Use lo.Compact instead. Returns slice excluding empty values.

Running example:
Result:
[1 3 5]
[1 2 3 4 5]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/intersection/without.go:36

Demo for search: demo for index of

Returns the index at which the first occurrence of a value is found in an array or return -1 if the value cannot be found.

Running example:
Result:
2
-1
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/index.go:21

Demo for search: demo for last index of

Returns the index at which the last occurrence of a value is found in an array or return -1 if the value cannot be found.

Running example:
Result:
3
-1
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/index.go:40

Demo for search: demo for find

Search an element in a slice based on a predicate. It returns element and true if element was found.

Running example:
Result:
2 true
0 false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/find.go:20

Demo for search: demo for find index of

FindIndexOf searches an element in a slice based on a predicate and returns the index and true. It returns -1 and false if the element is not found.

Running example:
demo for search

Demo for search: demo for find last index of

FindLastIndexOf searches an element in a slice based on a predicate and returns the index and true. It returns -1 and false if the element is not found.

Running example:
Result:
3 3 true
0 -1 false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/find.go:47

Demo for search: demo for find or else

FindOrElse searches an element in a slice based on a predicate and returns the element if found. It returns the default value if the element is not found.

Running example:
Result:
2
8848
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/find.go:64

Demo for search: demo for find key

Returns the key of the first value matching.

Running example:
Result:
ctrue
false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/find.go:81

Demo for search: demo for find key by

Returns the key of the first value matching the predicate.

Running example:
Result:
btrue
false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/find.go:98

Demo for search: demo for find uniques

Returns a slice with all the unique elements of the collection. The order of result values is determined by the order they occur in the array.

Running example:
Result:
[4 5]
[1 2 3 4 5]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/find.go:115

Demo for search: demo for find uniques by

Returns a slice with all the unique elements of the collection. The order of result values is determined by the order they occur in the array.

Running example:
Result:
[]
[3]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/find.go:132

Demo for search: demo for find duplicates

Returns a slice with all the duplicate elements of the collection.

Running example:
Result:
[1 2 3]
[]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/find.go:149

Demo for search: demo for find duplicates by

Returns a slice with all the duplicate elements of the collection.

Running example:
Result:
[1 2]
[1 2]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/find.go:166

Demo for search: demo for min

Returns the minimum element in a collection.

Running example:
Result:
1
1
0
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/min.go:22

Demo for search: demo for min by

Search the minimum value of a collection using the given comparison function. If several values of the collection are equal to the smallest value, returns the first such value. Returns zero value when the collection is empty.

Running example:
Result:
sit
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/min.go:44

Demo for search: demo for earliest

Search the minimum time.Time of a collection.

Running example:
Result:
0001-01-01 00:00:00 +0000 UTC
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/min.go:62

Demo for search: demo for earliest by

Search the minimum time.Time of a collection using the given comparison function.

Running example:
Result:
{{0 0 <nil>}}
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/min.go:88

Demo for search: demo for max

Returns the maximum element in a collection.

Running example:
Result:
5
5
0
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/min.go:104

Demo for search: demo for max by

Search the maximum value of a collection using the given comparison function.

Running example:
Result:
lorem
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/min.go:124

Demo for search: demo for latest

Search the maximum time.Time of a collection.

Running example:
Result:
2024-08-15 17:50:11.056968 +0800 +08 m=+0.865538543
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/min.go:142

Demo for search: demo for latest by

Search the maximum time.Time of a collection using the given comparison function.

Running example:
Result:
{{13954282175989648472 866081126 0x102d78700}}
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/min.go:168

Demo for search: demo for first

Returns the first element in a collection.

Running example:
Result:
1
true
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/first.go:19

Demo for search: demo for first or empty

Returns the first element in a collection or zero value if the collection is empty.

Running example:
Result:
1
0
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/first.go:33

Demo for search: demo for first or

Returns the first element in a collection or a default value.

Running example:
Result:
1
8848
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/first.go:52

Demo for search: demo for last

Returns the last element in a collection.

Running example:
Result:
5
true
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/first.go:71

Demo for search: demo for last or empty

Returns the last element in a collection or zero value if the collection is empty.

Running example:
Result:
5
0
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/first.go:87

Demo for search: demo for last or

Returns the last element in a collection or a default value.

Running example:
Result:
5
8848
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/first.go:106

Demo for search: demo for nth

Returns the nth element in a collection.

Running example:
Result:
3
<nil>
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/sample.go:19

Demo for search: demo for sample

Returns a random sample of elements from a collection.

Running example:
Result:
5
[3 4 1]
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/search/sample.go:33

Demo for conditional: demo for conditional statements

demo for conditional statements

Running example:
Result:
1
2
1
1
2
3
1
1
2
3
1
1
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/conditional/conditional.go:23

Demo for manipulation: demo for manipulation

demo for manipulation

Running example:
Result:
true
true
0x14000213000
<nil>
<nil>
&[]
0x14000213020
1
1
42
[0x1400022a078 0x1400022a080 0x1400022a088]
[1 2 3]
[hello world]
[1 2 3] true
{ 0}
true
true
hello worldtrue
hello world
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/manipulation/manipulation.go:27

Demo for function: demo for partial

demo for partial

Running example:
Result:
11
20
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/function/partial.go:28

Demo for concurrency: demo for attempt

Invokes a function N times until it returns valid output. Returning either the caught error or nil. When first argument is less than 1, the function runs until a successful response is returned.

Running example:
Result:
5 error
11 <nil>
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/concurrency/attempt.go:23

Demo for concurrency: demo for attempt with delay

Invokes a function N times with a delay until it returns valid output. Returning either the caught error or nil. When first argument is less than 1, the function runs until a successful response is returned.

Running example:
error and wait for 167ns
error and wait for 201.075833ms
error and wait for 401.397958ms
error and wait for 602.076583ms
error and wait for 803.277917ms
error and wait for 125ns
error and wait for 201.078625ms
error and wait for 402.225584ms
error and wait for 603.333459ms
error and wait for 804.351375ms
error and wait for 1.005465875s
error and wait for 1.206640417s
error and wait for 1.407695s
error and wait for 1.609014s
error and wait for 1.810154917s
Result:
5 803.405958ms error
11 2.012862667s <nil>
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/concurrency/attempt.go:48

Demo for concurrency: demo for attempt while

Invokes a function repeatedly until it returns true. Returning either the caught error or nil. When the predicate function returns false, the function stops.

Running example:
Result:
2 retryable error
6 non-retryable error
6 non-retryable error
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/concurrency/attempt.go:74

Demo for concurrency: demo for attempt while with delay

Invokes a function with a delay until it returns true. Returning either the caught error or nil. When the predicate function returns false, the function stops.

Running example:
retryable error and wait for 84ns
retryable error and wait for 200.70575ms
retryable error and wait for 41ns
retryable error and wait for 201.046458ms
retryable error and wait for 402.192ms
retryable error and wait for 602.662166ms
retryable error and wait for 803.6ms
non-retryable error and wait for 1.0047635s
retryable error and wait for 84ns
retryable error and wait for 201.149ms
retryable error and wait for 401.983917ms
retryable error and wait for 603.017917ms
retryable error and wait for 803.911334ms
non-retryable error and wait for 1.005056209s
Result:
2 200.809584ms retryable error
6 1.004858166s non-retryable error
6 1.005173209s non-retryable error
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/concurrency/attempt.go:103

Demo for concurrency: demo for debounce

NewDebounce creates a debounced instance that delays invoking functions given until after wait milliseconds have elapsed, until cancel is called.

Running example:
call once
will be debounced, if called multiple times within 10ms
call multiple times
will be debounced, if called multiple times within 10ms
will be debounced, if called multiple times within 10ms
will be debounced, if called multiple times within 10ms
will be debounced, if called multiple times within 10ms
will be debounced, if called multiple times within 10ms
will be debounced, if called multiple times within 10ms
will be debounced, if called multiple times within 10ms
will be debounced, if called multiple times within 10ms
will be debounced, if called multiple times within 10ms
cancel, nothing will be printed
Result:
done
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/concurrency/debounce.go:51

Demo for concurrency: demo for debounce by

count 让回调函数知道在防抖期间事件被触发了多少次, 而不仅仅是知道事件发生了. NewDebounceBy creates a debounced instance for each distinct key, that delays invoking functions given until sed, until cancel is called.

Running example:
键 'C' 被按下 1 次
键 'B' 被按下 2 次
键 'A' 被按下 4 次
Result:
done
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/concurrency/debounce.go:85

Demo for concurrency: demo for synchronize

Wraps the underlying callback in a mutex. It receives an optional mutex.

Running example:
Result:
true
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/concurrency/sync.go:37

Demo for concurrency: demo for async

Executes a function in a goroutine and returns the result in a channel.

Running example:
work2
work0
work1
work1
Result:
{}
1
1
{2 <nil>}
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/concurrency/sync.go:74

Demo for concurrency: demo for transact

Executes multiple functions in a single goroutine and returns the results in a channel.

Running example:
step 1
step 2
step 3
rollback 2
rollback 1
step 1
step 2
step 3
Result:
-5
too small
167
<nil>
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/concurrency/sync.go:133

Demo for concurrency: demo for wait for

Runs periodically until a condition is validated.

Running example:
Result:
1 2.274583ms true
10 10.138167ms false
7 7.118875ms true
2 10.366916ms false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/concurrency/wait_for.go:27

Demo for concurrency: demo for wait for with context

Runs periodically until a condition is validated or context is done.

Running example:
Result:
iterations: 1, duration: 2.267667ms, ok: true
iterations: 10, duration: 10.062833ms, ok: false
iterations: 6, duration: 6.121292ms, ok: true
iterations: 2, duration: 10.556542ms, ok: false
iterations: 7, duration: 31.215708ms, ok: true
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/concurrency/wait_for.go:72

Demo for error handling: Validate

Helper function that creates an error when a condition is not met.

Running example:
Result:
Slice should be empty but contains [a]
<nil>
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/error_handling/validate.go:22

Demo for error handling: ErrorAs

A shortcut for:

err := doSomething() var rateLimitErr *RateLimitError if ok := errors.As(err, &rateLimitErr); ok { // retry later }

Running example:
Result:
my error true
 false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/error_handling/validate.go:60

Demo for error handling: Must

Wraps a function call to panics if second argument is error or false, returns the value otherwise.

Running example:
Result:
2022-01-15 00:00:00 +0000 UTC
1 2 3
2022-01-15 00:00:00 +0000 UTC
1 2 3
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/error_handling/must.go:31

Demo for error handling: Try

Calls the function and returns false in case of error and panic.

Running example:
Result:
false
true
false
false
true
false
8848 false
1 true
8848 false
1 2 3 false
1 2 3 true
1 2 3 false
errorfalse
<nil> true
error false
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/error_handling/try.go:20

Demo for error handling: TryCatch

Calls the function and returns the error in case of error.

Running example:
catch: error
Result:
done
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/error_handling/try.go:62

Demo for error handling: TryCatchWithErrorValue

The same behavior as TryWithErrorValue, but calls the catch function in case of error.

Running example:
catch: trigger an error
Result:
done
Source: /Users/bytedance/Desktop/Projects/2024/q3/lo-learn/error_handling/try.go:84