fmlist-0.4: FoldMap lists

Portability portable experimental sjoerd

Data.FMList

Contents

Description

FoldMap lists: lists represented by their foldMap function.

Synopsis

# Documentation

newtype FMList a Source

FMList is a foldMap function wrapped up in a newtype. Examples:

``` -- A right-infinite list
c = 1 `cons` c
```
``` -- A left-infinite list
d = d `snoc` 2
```
``` -- A middle-infinite list ??
e = c `append` d
```
``` *> head e
1
*> last e
2
```

Constructors

 FM FieldsunFM :: forall b. Monoid b => (a -> b) -> b

Instances

 Monad FMList Functor FMList MonadPlus FMList Applicative FMList Foldable FMList Traversable FMList Alternative FMList Show a => Show (FMList a) Monoid (FMList a)

transform :: (forall b. Monoid b => (a -> b) -> c -> b) -> FMList c -> FMList aSource

Transform transforms a list by changing the map function that is passed to foldMap. It has the following property:

`transform a . transform b = transform (b . a)`

For example:

• `  m >>= g`
• `= flatten (fmap g m)`
• `= flatten . fmap g \$ m`
• `= transform foldMap . transform (. g) \$ m`
• `= transform ((. g) . foldMap) m`
• `= transform (\f -> foldMap f . g) m`

# Construction

empty :: Alternative f => forall a. f a

The identity of `<|>`

cons :: a -> FMList a -> FMList aSource

snoc :: FMList a -> a -> FMList aSource

toList :: Foldable t => t a -> [a]

List of elements of a structure.

# Basic functions

head :: FMList a -> aSource

last :: FMList a -> aSource

# Folding

filter :: (a -> Bool) -> FMList a -> FMList aSource

take :: (Ord n, Num n) => n -> FMList a -> FMList aSource

drop :: (Ord n, Num n) => n -> FMList a -> FMList aSource

takeWhile :: (a -> Bool) -> FMList a -> FMList aSource

dropWhile :: (a -> Bool) -> FMList a -> FMList aSource

zip :: FMList a -> FMList b -> FMList (a, b)Source

zipWith :: (a -> b -> c) -> FMList a -> FMList b -> FMList cSource

# Unfolding

iterate :: (a -> a) -> a -> FMList aSource

unfoldr :: (b -> Maybe (a, b)) -> b -> FMList aSource

unfoldl :: (b -> Maybe (b, a)) -> b -> FMList aSource