Module

Data.Either.Nested

Utilities for n-eithers: sums types with more than two terms built from nested eithers.

Nested eithers arise naturally in sum combinators. You shouldn't represent sum data using nested eithers, but if combinators you're working with create them, utilities in this module will allow to to more easily work with them, including translating to and from more traditional sum types.

data Color = Red Number | Green Number | Blue Number

fromEither3 :: Either3 Number Number Number -> Color
fromEither3 = either3 Red Green Blue

toEither3 :: Color -> Either3 Number Number Number
toEither3 (Red   v) = in1 v
toEither3 (Green v) = in2 v
toEither3 (Blue  v) = in3 v

#type (\/)

Operator alias for Data.Either.Either (right-associative / precedence 6)

#(\/)

Operator alias for Data.Either.either (right-associative / precedence 6)

The \/ operator alias for the either function allows easy matching on nested Eithers. For example, consider the function

f :: (Int \/ String \/ Boolean) -> String
f (Left x) = show x
f (Right (Left y)) = y
f (Right (Right z)) = if z then "Yes" else "No"

The \/ operator alias allows us to rewrite this function as

f :: (Int \/ String \/ Boolean) -> String
f = show \/ identity \/ if _ then "Yes" else "No"

#in1 

in1 :: forall a z. a -> a \/ z

#in2 

in2 :: forall a b z. b -> a \/ b \/ z

#in3 

in3 :: forall a b c z. c -> a \/ b \/ c \/ z

#in4 

in4 :: forall a b c d z. d -> a \/ b \/ c \/ d \/ z

#in5 

in5 :: forall a b c d e z. e -> a \/ b \/ c \/ d \/ e \/ z

#in6 

in6 :: forall a b c d e f z. f -> a \/ b \/ c \/ d \/ e \/ f \/ z

#in7 

in7 :: forall a b c d e f g z. g -> a \/ b \/ c \/ d \/ e \/ f \/ g \/ z

#in8 

in8 :: forall a b c d e f g h z. h -> a \/ b \/ c \/ d \/ e \/ f \/ g \/ h \/ z

#in9 

in9 :: forall a b c d e f g h i z. i -> a \/ b \/ c \/ d \/ e \/ f \/ g \/ h \/ i \/ z

#in10 

in10 :: forall a b c d e f g h i j z. j -> a \/ b \/ c \/ d \/ e \/ f \/ g \/ h \/ i \/ j \/ z

#at1 

at1 :: forall r a z. r -> (a -> r) -> a \/ z -> r

#at2 

at2 :: forall r a b z. r -> (b -> r) -> a \/ b \/ z -> r

#at3 

at3 :: forall r a b c z. r -> (c -> r) -> a \/ b \/ c \/ z -> r

#at4 

at4 :: forall r a b c d z. r -> (d -> r) -> a \/ b \/ c \/ d \/ z -> r

#at5 

at5 :: forall r a b c d e z. r -> (e -> r) -> a \/ b \/ c \/ d \/ e \/ z -> r

#at6 

at6 :: forall r a b c d e f z. r -> (f -> r) -> a \/ b \/ c \/ d \/ e \/ f \/ z -> r

#at7 

at7 :: forall r a b c d e f g z. r -> (g -> r) -> a \/ b \/ c \/ d \/ e \/ f \/ g \/ z -> r

#at8 

at8 :: forall r a b c d e f g h z. r -> (h -> r) -> a \/ b \/ c \/ d \/ e \/ f \/ g \/ h \/ z -> r

#at9 

at9 :: forall r a b c d e f g h i z. r -> (i -> r) -> a \/ b \/ c \/ d \/ e \/ f \/ g \/ h \/ i \/ z -> r

#at10 

at10 :: forall r a b c d e f g h i j z. r -> (j -> r) -> a \/ b \/ c \/ d \/ e \/ f \/ g \/ h \/ i \/ j \/ z -> r

#Either1 

type Either1 a = a \/ Void

#Either2 

type Either2 a b = a \/ b \/ Void

#Either3 

type Either3 a b c = a \/ b \/ c \/ Void

#Either4 

type Either4 a b c d = a \/ b \/ c \/ d \/ Void

#Either5 

type Either5 a b c d e = a \/ b \/ c \/ d \/ e \/ Void

#Either6 

type Either6 a b c d e f = a \/ b \/ c \/ d \/ e \/ f \/ Void

#Either7 

type Either7 a b c d e f g = a \/ b \/ c \/ d \/ e \/ f \/ g \/ Void

#Either8 

type Either8 a b c d e f g h = a \/ b \/ c \/ d \/ e \/ f \/ g \/ h \/ Void

#Either9 

type Either9 a b c d e f g h i = a \/ b \/ c \/ d \/ e \/ f \/ g \/ h \/ i \/ Void

#Either10 

type Either10 a b c d e f g h i j = a \/ b \/ c \/ d \/ e \/ f \/ g \/ h \/ i \/ j \/ Void

#either1 

either1 :: forall a. Either1 a -> a

#either2 

either2 :: forall r a b. (a -> r) -> (b -> r) -> Either2 a b -> r

#either3 

either3 :: forall r a b c. (a -> r) -> (b -> r) -> (c -> r) -> Either3 a b c -> r

#either4 

either4 :: forall r a b c d. (a -> r) -> (b -> r) -> (c -> r) -> (d -> r) -> Either4 a b c d -> r

#either5 

either5 :: forall r a b c d e. (a -> r) -> (b -> r) -> (c -> r) -> (d -> r) -> (e -> r) -> Either5 a b c d e -> r

#either6 

either6 :: forall r a b c d e f. (a -> r) -> (b -> r) -> (c -> r) -> (d -> r) -> (e -> r) -> (f -> r) -> Either6 a b c d e f -> r

#either7 

either7 :: forall r a b c d e f g. (a -> r) -> (b -> r) -> (c -> r) -> (d -> r) -> (e -> r) -> (f -> r) -> (g -> r) -> Either7 a b c d e f g -> r

#either8 

either8 :: forall r a b c d e f g h. (a -> r) -> (b -> r) -> (c -> r) -> (d -> r) -> (e -> r) -> (f -> r) -> (g -> r) -> (h -> r) -> Either8 a b c d e f g h -> r

#either9 

either9 :: forall r a b c d e f g h i. (a -> r) -> (b -> r) -> (c -> r) -> (d -> r) -> (e -> r) -> (f -> r) -> (g -> r) -> (h -> r) -> (i -> r) -> Either9 a b c d e f g h i -> r

#either10 

either10 :: forall r a b c d e f g h i j. (a -> r) -> (b -> r) -> (c -> r) -> (d -> r) -> (e -> r) -> (f -> r) -> (g -> r) -> (h -> r) -> (i -> r) -> (j -> r) -> Either10 a b c d e f g h i j -> r

Modules