| Copyright | (c) Adam Conner-Sax 2019 |
|---|---|
| License | BSD |
| Maintainer | adam_conner_sax@yahoo.com |
| Stability | experimental |
| Safe Haskell | None |
| Language | Haskell2010 |
Frames.Folds.General
Contents
Description
Frames.Folds contains various helper functions designed to simplify folding over Frames/Vinyl records given some way of folding over each column.
Synopsis
- type EndoFold a = Fold a a
- newtype FoldEndo f t = FoldEndo {
- unFoldEndo :: EndoFold (f (Snd t))
- newtype FoldRecord record f g rs a = FoldRecord {
- unFoldRecord :: Fold (record (f :. ElField) rs) (g a)
- class EndoFieldFoldsToRecordFolds rs record f
- class c (Snd t) => ConstrainedField c t
- toFoldRecord :: (a -> g b) -> Fold (record (f :. ElField) rs) a -> FoldRecord record f g rs b
- recFieldF :: forall t rs a record f. (KnownField t, Applicative f) => (forall x. f x -> Maybe x) -> Fold a (Snd t) -> (record (f :. ElField) rs -> f a) -> FoldRecord record f (f :. ElField) rs t
- fieldToFieldFold :: forall x y rs record f. (KnownField x, KnownField y, ElemOf rs x, RecGetFieldC x record f rs, Applicative f) => (forall z. f z -> Maybe z) -> Fold (Snd x) (Snd y) -> FoldRecord record f (f :. ElField) rs y
- sequenceRecFold :: forall as rs record f. IsoRec rs record f => Rec (FoldRecord record f (f :. ElField) as) rs -> Fold (record (f :. ElField) as) (record (f :. ElField) rs)
- sequenceEndoFolds :: forall rs record f. (RApply rs, RPureConstrained KnownField rs, EndoFieldFoldsToRecordFolds rs record f, IsoRec rs record f, Functor f) => Rec (FoldEndo f) rs -> Fold (record (f :. ElField) rs) (record (f :. ElField) rs)
- foldAll :: (RPureConstrained KnownField rs, RApply rs, EndoFieldFoldsToRecordFolds rs record f, IsoRec rs record f, Functor f) => (forall a. Fold a a) -> Fold (record (f :. ElField) rs) (record (f :. ElField) rs)
- foldAllConstrained :: forall c rs record f. (RPureConstrained (ConstrainedField c) rs, RPureConstrained KnownField rs, RApply rs, EndoFieldFoldsToRecordFolds rs record f, IsoRec rs record f, Applicative f) => (forall a. f a -> Maybe a) -> (forall a. c a => Fold a a) -> Fold (record (f :. ElField) rs) (record (f :. ElField) rs)
- functorFoldAllConstrained :: forall c rs record f. (RPureConstrained (ConstrainedField c) rs, RPureConstrained KnownField rs, RApply rs, EndoFieldFoldsToRecordFolds rs record f, IsoRec rs record f, Applicative f) => (forall a. c a => Fold (f a) (f a)) -> Fold (record (f :. ElField) rs) (record (f :. ElField) rs)
- foldAllMonoid :: forall g rs record f. (RPureConstrained (ConstrainedField (MonoidalField g)) rs, RPureConstrained KnownField rs, RApply rs, EndoFieldFoldsToRecordFolds rs record f, IsoRec rs record f, Applicative f) => (forall a. f a -> Maybe a) -> Fold (record (f :. ElField) rs) (record (f :. ElField) rs)
Types
Types to act as "interpretation functors" for records of folds
Wrapper for Endo-folds of the field types of ElFields
Constructors
| FoldEndo | |
Fields
| |
newtype FoldRecord record f g rs a Source #
Wrapper for folds from a record to an interpreted field. Usually g ~ ElField
Constructors
| FoldRecord | |
Fields
| |
classes
class EndoFieldFoldsToRecordFolds rs record f Source #
Change a record of single field folds to a record of folds from the entire record to each field
Minimal complete definition
endoFieldFoldsToRecordFolds
Instances
| EndoFieldFoldsToRecordFolds ([] :: [(Symbol, Type)]) record f Source # | |
Defined in Frames.Folds.General Methods endoFieldFoldsToRecordFolds :: Rec (FoldFieldEndo (f :. ElField)) [] -> Rec (FoldRecord record f (f :. ElField) []) [] | |
| (EndoFieldFoldsToRecordFolds rs record f, RCastC rs (r ': rs) record f, KnownField r, RecGetFieldC r record f (r ': rs), RMap rs) => EndoFieldFoldsToRecordFolds (r ': rs) record f Source # | |
Defined in Frames.Folds.General Methods endoFieldFoldsToRecordFolds :: Rec (FoldFieldEndo (f :. ElField)) (r ': rs) -> Rec (FoldRecord record f (f :. ElField) (r ': rs)) (r ': rs) | |
class c (Snd t) => ConstrainedField c t Source #
Instances
| c (Snd t) => ConstrainedField (c :: k -> Constraint) (t :: (k1, k)) Source # | |
Defined in Frames.Folds.General | |
functions for building records of folds
toFoldRecord :: (a -> g b) -> Fold (record (f :. ElField) rs) a -> FoldRecord record f g rs b Source #
Create a FoldRecord from a Fold from a record to a specific type.
This is helpful when creating folds from a record to another record (or the same record)
by building it one field at a time. See examples for details.
Arguments
| :: (KnownField t, Applicative f) | |
| => (forall x. f x -> Maybe x) | |
| -> Fold a (Snd t) | A fold from some type a to the field type of an ElField |
| -> (record (f :. ElField) rs -> f a) | |
| -> FoldRecord record f (f :. ElField) rs t | the resulting |
Helper for building a FoldRecord from a given fold and function of the record
Arguments
| :: (KnownField x, KnownField y, ElemOf rs x, RecGetFieldC x record f rs, Applicative f) | |
| => (forall z. f z -> Maybe z) | |
| -> Fold (Snd x) (Snd y) | the fold to be wrapped |
| -> FoldRecord record f (f :. ElField) rs y | the wrapped fold |
special case of recFieldF for the case when the function from the record to the folded type
is just retrieving the value in a field.
functions for turning records of folds into folds of records
sequenceRecFold :: forall as rs record f. IsoRec rs record f => Rec (FoldRecord record f (f :. ElField) as) rs -> Fold (record (f :. ElField) as) (record (f :. ElField) rs) Source #
Turn a Record of folds into a fold over records
sequenceEndoFolds :: forall rs record f. (RApply rs, RPureConstrained KnownField rs, EndoFieldFoldsToRecordFolds rs record f, IsoRec rs record f, Functor f) => Rec (FoldEndo f) rs -> Fold (record (f :. ElField) rs) (record (f :. ElField) rs) Source #
turn a record of endo-folds over each field, into a fold over records
functions using constraints to extend an endo-fold across a record
foldAll :: (RPureConstrained KnownField rs, RApply rs, EndoFieldFoldsToRecordFolds rs record f, IsoRec rs record f, Functor f) => (forall a. Fold a a) -> Fold (record (f :. ElField) rs) (record (f :. ElField) rs) Source #
apply an unconstrained endo-fold, e.g., a fold which takes the last item in a container, to every field in a record
foldAllConstrained :: forall c rs record f. (RPureConstrained (ConstrainedField c) rs, RPureConstrained KnownField rs, RApply rs, EndoFieldFoldsToRecordFolds rs record f, IsoRec rs record f, Applicative f) => (forall a. f a -> Maybe a) -> (forall a. c a => Fold a a) -> Fold (record (f :. ElField) rs) (record (f :. ElField) rs) Source #
Apply a constrained endo-fold to all fields of a record. May require a use of TypeApplications, e.g., foldAllConstrained @Num FL.sum
functorFoldAllConstrained :: forall c rs record f. (RPureConstrained (ConstrainedField c) rs, RPureConstrained KnownField rs, RApply rs, EndoFieldFoldsToRecordFolds rs record f, IsoRec rs record f, Applicative f) => (forall a. c a => Fold (f a) (f a)) -> Fold (record (f :. ElField) rs) (record (f :. ElField) rs) Source #
foldAllMonoid :: forall g rs record f. (RPureConstrained (ConstrainedField (MonoidalField g)) rs, RPureConstrained KnownField rs, RApply rs, EndoFieldFoldsToRecordFolds rs record f, IsoRec rs record f, Applicative f) => (forall a. f a -> Maybe a) -> Fold (record (f :. ElField) rs) (record (f :. ElField) rs) Source #
Given a monoid-wrapper, e.g., Sum, apply the derived endo-fold to all fields of a record This is strictly less powerful than foldAllConstrained but might be simpler to use in some cases