Conditional - Core helpers

This page lists all conditional operations available in the core package of lo.

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• Ternary

  conditioncore

  🧩 Source📚 GoDoc🎮 Try on Go Playground

  A single-line if/else that returns ifOutput when condition is true, otherwise elseOutput.

  result := lo.Ternary(true, "a", "b")
  // result: "a"
  
  result = lo.Ternary(false, "a", "b")
  // result: "b"
  
  // With numbers
  age := 25
  status := lo.Ternary(age >= 18, "adult", "minor")
  // status: "adult"
  
  // With complex expressions
  x, y := 10, 20
  max := lo.Ternary(x > y, x, y)
  // max: 20

  TernaryF - Function Form

  Function form of Ternary. Lazily evaluates the selected branch to avoid unnecessary work or nil dereferences.

  var s *string
  str := lo.TernaryF(s == nil, func() string {
      return uuid.New().String()
  }, func() string {
      return *s
  })
  // str: newly generated UUID (since s is nil)
  
  // Example with expensive operations
  str = "hello"
  result := lo.TernaryF(s != nil, func() string {
      return *s // safe dereference only when s is not nil
  }, func() string {
      return "default value"
  })
  // result: "hello"
  
  // Performance benefit - only executes needed branch
  result = lo.TernaryF(false, func() string {
      time.Sleep(1 * time.Second) // this won't execute
      return "slow operation"
  }, func() string {
      return "fast operation" // only this executes
  })
  // result: "fast operation" (returns immediately)

  Variant:

  ternaryf

  Similar:

  ifpartialxswitchvalidate

  Prototypes:

  func Ternary[T any](condition bool, ifOutput T, elseOutput T) T
  func TernaryF[T any](condition bool, ifFunc func() T, elseFunc func() T) T

• If/Else

  conditioncore

  🧩 Source📚 GoDoc🎮 Try on Go Playground

  A fluent conditional builder that allows chaining If/ElseIf/Else conditions.

  If

  Starts a fluent If/ElseIf/Else chain. Returns a builder that can be completed with ElseIf, Else, etc.

  result := lo.If(true, 1).Else(3)
  // 1

  IfF

  Function form of If. Lazily computes the initial result when the condition is true.

  result := lo.IfF(true, func() int {
      return 1
  }).Else(3)
  // 1

  ElseIf

  Adds an ElseIf branch to an If/Else chain.

  result := lo.If(false, 1).ElseIf(true, 2).Else(3)
  // 2

  ElseIfF

  Function form of ElseIf. Lazily computes the branch result when the condition is true.

  result := lo.If(false, 1).ElseIfF(true, func() int {
      return 2
  }).Else(3)
  // 2

  Else

  Completes the If/Else chain by returning the chosen result or the default provided here.

  result := lo.If(false, 1).ElseIf(false, 2).Else(3)
  // 3

  ElseF

  Function form of Else. Lazily computes the default result if no previous branch matched.

  result := lo.If(false, 1).ElseIf(false, 2).ElseF(func() int {
      return 3
  })
  // 3

  Variant:

  ififf

  Similar:

  switchternaryvalidate

  Prototypes:

  func If[T any](condition bool, result T) *ifElse[T]
  func IfF[T any](condition bool, resultF func() T) *ifElse[T]
  func (i *ifElse[T]) ElseIf(condition bool, result T) *ifElse[T]
  func (i *ifElse[T]) ElseIfF(condition bool, resultF func() T) *ifElse[T]
  func (i *ifElse[T]) Else(result T) T
  func (i *ifElse[T]) ElseF(resultF func() T) T

• Switch

  conditioncore

  🧩 Source📚 GoDoc🎮 Try on Go Playground

  Starts a functional switch/case/default chain using a predicate value.

  result := lo.Switch(2).Case(1, "1").Case(2, "2").Default("3")
  // "2"

  Case

  Adds a Case branch to a Switch chain returning a constant result.

  result := lo.Switch(1).Case(1, "1").Default("?")
  // "1"

  CaseF

  Adds a Case branch that lazily computes its result.

  result := lo.Switch(2).CaseF(2, func() string {
      return "2"
  }).Default("?")
  // "2"

  Default

  Completes the Switch chain by providing a default result when no Case matched.

  result := lo.Switch(42).Default("none")
  // "none"

  DefaultF

  Function form of Default. Lazily computes the default result when no Case matched.

  result := lo.Switch(0).Case(1, "1").DefaultF(func() string {
      return "3"
  })
  // "3"

  Variant:

  casecasefdefaultdefaultf

  Similar:

  ifternaryvalidate

  Prototypes:

  func Switch[T comparable, R any](predicate T) *switchCase[T, R]
  func (s *switchCase[T, R]) Case(val T, result R) *switchCase[T, R]
  func (s *switchCase[T, R]) CaseF(val T, callback func() R) *switchCase[T, R]
  func (s *switchCase[T, R]) Default(result R) R
  func (s *switchCase[T, R]) DefaultF(callback func() R) R