Documentation

Write like the following.

enum "Foo" ''Int [''Show, ''Read, ''Eq] [
	("FooError", - 1),
	("FooZero", 0),
	("FooOne", 1),
	("FooTwo", 2) ]

Then you get like the following.

newtype Foo = Foo Int deriving Eq

pattern FooError :: Int -> Foo
pattern FooError <- Foo (- 1) where
	FooError = Foo (- 1)

pattern FooZero :: Int -> Foo
...


instance Show Foo where
	showsPrec = ...

instance Read Foo where
	readPrec = ...

And you can read and show like the following.

> Foo $ - 1
FooError
> FooTwo
FooTwo
> Foo 3
Foo 3
> read "Foo (- 1)" :: Foo
FooError
> read "FooOne" :: Foo
FooOne

You can define enum members separately.

enumMems "Foo" [
	("FooThree", 3),
	("FooFour", 4) ]