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Merge branch 'master' of github.com:samber/mo
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@samber
samber committed Aug 28, 2022
2 parents 9698fba + a9c34fb commit 1243361
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Showing 3 changed files with 38 additions and 41 deletions.
47 changes: 22 additions & 25 deletions either.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -9,26 +9,23 @@ var eitherMissingRightValue = fmt.Errorf("no such Right value")
// Left builds the left side of the Either struct, as opposed to the Right side.
func Left[L any, R any](value L) Either[L, R] {
return Either[L, R]{
isLeft: true,
isRight: false,
left: value,
isLeft: true,
left: value,
}
}

// Right builds the right side of the Either struct, as opposed to the Left side.
func Right[L any, R any](value R) Either[L, R] {
return Either[L, R]{
isLeft: false,
isRight: true,
right: value,
isLeft: false,
right: value,
}
}

// Either respresents a value of 2 possible types.
// An instance of Either is an instance of either A or B.
type Either[L any, R any] struct {
isLeft bool
isRight bool
isLeft bool

left L
right R
Expand All @@ -41,28 +38,28 @@ func (e Either[L, R]) IsLeft() bool {

// IsRight returns true if Either is an instance of Right.
func (e Either[L, R]) IsRight() bool {
return e.isRight
return !e.isLeft
}

// Left returns left value of a Either struct.
func (e Either[L, R]) Left() (L, bool) {
if e.isLeft {
if e.IsLeft() {
return e.left, true
}
return empty[L](), false
}

// Right returns right value of a Either struct.
func (e Either[L, R]) Right() (R, bool) {
if e.isRight {
if e.IsRight() {
return e.right, true
}
return empty[R](), false
}

// MustLeft returns left value of a Either struct or panics.
func (e Either[L, R]) MustLeft() L {
if !e.isLeft {
if !e.IsLeft() {
panic(eitherMissingLeftValue)
}

Expand All @@ -71,7 +68,7 @@ func (e Either[L, R]) MustLeft() L {

// MustRight returns right value of a Either struct or panics.
func (e Either[L, R]) MustRight() R {
if !e.isRight {
if !e.IsRight() {
panic(eitherMissingRightValue)
}

Expand All @@ -80,7 +77,7 @@ func (e Either[L, R]) MustRight() R {

// LeftOrElse returns left value of a Either struct or fallback.
func (e Either[L, R]) LeftOrElse(fallback L) L {
if e.isLeft {
if e.IsLeft() {
return e.left
}

Expand All @@ -89,7 +86,7 @@ func (e Either[L, R]) LeftOrElse(fallback L) L {

// RightOrElse returns right value of a Either struct or fallback.
func (e Either[L, R]) RightOrElse(fallback R) R {
if e.isRight {
if e.IsRight() {
return e.right
}

Expand All @@ -98,7 +95,7 @@ func (e Either[L, R]) RightOrElse(fallback R) R {

// LeftOrEmpty returns left value of a Either struct or empty value.
func (e Either[L, R]) LeftOrEmpty() L {
if e.isLeft {
if e.IsLeft() {
return e.left
}

Expand All @@ -107,7 +104,7 @@ func (e Either[L, R]) LeftOrEmpty() L {

// RightOrEmpty returns right value of a Either struct or empty value.
func (e Either[L, R]) RightOrEmpty() R {
if e.isRight {
if e.IsRight() {
return e.right
}

Expand All @@ -116,7 +113,7 @@ func (e Either[L, R]) RightOrEmpty() R {

// Swap returns the left value in Right and vice versa.
func (e Either[L, R]) Swap() Either[R, L] {
if e.isLeft {
if e.IsLeft() {
return Right[R, L](e.left)
}

Expand All @@ -125,18 +122,18 @@ func (e Either[L, R]) Swap() Either[R, L] {

// ForEach executes the given side-effecting function, depending of value is Left or Right.
func (e Either[L, R]) ForEach(leftCb func(L), rightCb func(R)) {
if e.isLeft {
if e.IsLeft() {
leftCb(e.left)
} else if e.isRight {
} else if e.IsRight() {
rightCb(e.right)
}
}

// Match executes the given function, depending of value is Left or Right, and returns result.
func (e Either[L, R]) Match(onLeft func(L) Either[L, R], onRight func(R) Either[L, R]) Either[L, R] {
if e.isLeft {
if e.IsLeft() {
return onLeft(e.left)
} else if e.isRight {
} else if e.IsRight() {
return onRight(e.right)
}

Expand All @@ -145,9 +142,9 @@ func (e Either[L, R]) Match(onLeft func(L) Either[L, R], onRight func(R) Either[

// MapLeft executes the given function, if Either is of type Left, and returns result.
func (e Either[L, R]) MapLeft(mapper func(L) Either[L, R]) Either[L, R] {
if e.isLeft {
if e.IsLeft() {
return mapper(e.left)
} else if e.isRight {
} else if e.IsRight() {
return Right[L, R](e.right)
}

Expand All @@ -158,7 +155,7 @@ func (e Either[L, R]) MapLeft(mapper func(L) Either[L, R]) Either[L, R] {
func (e Either[L, R]) MapRight(mapper func(R) Either[L, R]) Either[L, R] {
if e.isLeft {
return Left[L, R](e.left)
} else if e.isRight {
} else if e.IsRight() {
return mapper(e.right)
}

Expand Down
20 changes: 10 additions & 10 deletions either_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -10,14 +10,14 @@ func TestEitherLeft(t *testing.T) {
is := assert.New(t)

left := Left[int, bool](42)
is.Equal(Either[int, bool]{left: 42, right: false, isLeft: true, isRight: false}, left)
is.Equal(Either[int, bool]{left: 42, right: false, isLeft: true}, left)
}

func TestEitherRight(t *testing.T) {
is := assert.New(t)

right := Right[int, bool](true)
is.Equal(Either[int, bool]{left: 0, right: true, isLeft: false, isRight: true}, right)
is.Equal(Either[int, bool]{left: 0, right: true, isLeft: false}, right)
}

func TestEitherIsLeftOrRight(t *testing.T) {
Expand Down Expand Up @@ -103,8 +103,8 @@ func TestEitherSwap(t *testing.T) {
left := Left[int, string](42)
right := Right[int, string]("foobar")

is.Equal(Either[string, int]{left: "", right: 42, isLeft: false, isRight: true}, left.Swap())
is.Equal(Either[string, int]{left: "foobar", right: 0, isLeft: true, isRight: false}, right.Swap())
is.Equal(Either[string, int]{left: "", right: 42, isLeft: false}, left.Swap())
is.Equal(Either[string, int]{left: "foobar", right: 0, isLeft: true}, right.Swap())
}

func TestEitherForEach(t *testing.T) {
Expand Down Expand Up @@ -154,8 +154,8 @@ func TestEitherMatch(t *testing.T) {
},
)

is.Equal(Either[int, string]{left: 21, right: "", isLeft: true, isRight: false}, e1)
is.Equal(Either[int, string]{left: 0, right: "plop", isLeft: false, isRight: true}, e2)
is.Equal(Either[int, string]{left: 21, right: "", isLeft: true}, e1)
is.Equal(Either[int, string]{left: 0, right: "plop", isLeft: false}, e2)
}

func TestEitherMapLeft(t *testing.T) {
Expand All @@ -175,8 +175,8 @@ func TestEitherMapLeft(t *testing.T) {
},
)

is.Equal(Either[int, string]{left: 21, right: "", isLeft: true, isRight: false}, e1)
is.Equal(Either[int, string]{left: 0, right: "foobar", isLeft: false, isRight: true}, e2)
is.Equal(Either[int, string]{left: 21, right: "", isLeft: true}, e1)
is.Equal(Either[int, string]{left: 0, right: "foobar", isLeft: false}, e2)
}

func TestEitherMapRight(t *testing.T) {
Expand All @@ -196,6 +196,6 @@ func TestEitherMapRight(t *testing.T) {
},
)

is.Equal(Either[int, string]{left: 42, right: "", isLeft: true, isRight: false}, e1)
is.Equal(Either[int, string]{left: 0, right: "plop", isLeft: false, isRight: true}, e2)
is.Equal(Either[int, string]{left: 42, right: "", isLeft: true}, e1)
is.Equal(Either[int, string]{left: 0, right: "plop", isLeft: false}, e2)
}
12 changes: 6 additions & 6 deletions io_either_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ func TestIOEither(t *testing.T) {

is.False(result.isLeft)
is.Nil(result.Left())
is.True(result.isRight)
is.True(result.IsRight())
is.Equal(42, result.MustRight())
}

Expand All @@ -31,7 +31,7 @@ func TestIOEither1(t *testing.T) {

is.False(result.isLeft)
is.Nil(result.Left())
is.True(result.isRight)
is.True(result.IsRight())
is.Equal(42, result.MustRight())
}

Expand All @@ -47,7 +47,7 @@ func TestIOEither2(t *testing.T) {

is.False(result.isLeft)
is.Nil(result.Left())
is.True(result.isRight)
is.True(result.IsRight())
is.Equal(42, result.MustRight())
}

Expand All @@ -64,7 +64,7 @@ func TestIOEither3(t *testing.T) {

is.False(result.isLeft)
is.Nil(result.Left())
is.True(result.isRight)
is.True(result.IsRight())
is.Equal(42, result.MustRight())
}

Expand All @@ -82,7 +82,7 @@ func TestIOEither4(t *testing.T) {

is.False(result.isLeft)
is.Nil(result.Left())
is.True(result.isRight)
is.True(result.IsRight())
is.Equal(42, result.MustRight())
}

Expand All @@ -101,6 +101,6 @@ func TestIOEither5(t *testing.T) {

is.False(result.isLeft)
is.Nil(result.Left())
is.True(result.isRight)
is.True(result.IsRight())
is.Equal(42, result.MustRight())
}

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