Strongweak.Generic.Strengthen

strengthen over generic representations.

Strengthen failures are annotated with precise information describing where the failure occurred: datatype name, constructor name, field index (and name if present). To achieve this, we split the generic derivation into 3 classes, each handling/"unwrapping" a different layer of the generic representation: datatype (D), constructor (C) and selector (S).

Documentation

strengthenGeneric :: (Generic w, Generic s, GStrengthenD (Rep w) (Rep s)) => w -> Validation (NonEmpty StrengthenFail) s

Strengthen a value generically.

The weak and strong types must be compatible. See Generic for the definition of compatibility in this context.

class GStrengthenD w s where

Generic strengthening at the datatype level.

Methods

gstrengthenD :: w p -> Validation (NonEmpty StrengthenFail) (s p)

Instances

(GStrengthenC w s, Datatype dw, Datatype ds) => GStrengthenD (D1 dw w :: k -> Type) (D1 ds s :: k -> Type)

Enter a datatype, stripping its metadata wrapper.

Defined in Strongweak.Generic.Strengthen

Methods

gstrengthenD :: forall (p :: k0). D1 dw w p -> Validation (NonEmpty StrengthenFail) (D1 ds s p)

class GStrengthenC w s where

Generic strengthening at the constructor sum level.

Methods

gstrengthenC :: String -> String -> w p -> Validation (NonEmpty StrengthenFail) (s p)

Instances

GStrengthenC (V1 :: k -> Type) (V1 :: k -> Type)

Nothing to do for empty datatypes.

Defined in Strongweak.Generic.Strengthen

Methods

gstrengthenC :: forall (p :: k0). String -> String -> V1 p -> Validation (NonEmpty StrengthenFail) (V1 p)

(GStrengthenC lw ls, GStrengthenC rw rs) => GStrengthenC (lw :+: rw :: k -> Type) (ls :+: rs :: k -> Type)

Strengthen sum types by casing and strengthening left or right.

Defined in Strongweak.Generic.Strengthen

Methods

gstrengthenC :: forall (p :: k0). String -> String -> (lw :+: rw) p -> Validation (NonEmpty StrengthenFail) ((ls :+: rs) p)

(GStrengthenS w s, Constructor cw, Constructor cs) => GStrengthenC (C1 cw w :: k -> Type) (C1 cs s :: k -> Type)

Enter a constructor, stripping its metadata wrapper.

Defined in Strongweak.Generic.Strengthen

Methods

gstrengthenC :: forall (p :: k0). String -> String -> C1 cw w p -> Validation (NonEmpty StrengthenFail) (C1 cs s p)

class GStrengthenS w s where

Generic strengthening at the selector product level.

In order to calculate field indices, we return the current field index alongside the result. This way, the product case can strengthen the left branch, then increment the returned field index and use it for strengthening the right branch.

Methods

gstrengthenS

Arguments

:: String

weak datatype name

-> String

strong datatype name

-> String

weak constructor name

-> String

strong constructor name

-> Natural

current field index (0, from left)

-> w p

-> (Natural, Validation (NonEmpty StrengthenFail) (s p))

Instances

GStrengthenS (U1 :: k -> Type) (U1 :: k -> Type)

Nothing to do for empty constructors.

Defined in Strongweak.Generic.Strengthen

Methods

gstrengthenS :: forall (p :: k0). String -> String -> String -> String -> Natural -> U1 p -> (Natural, Validation (NonEmpty StrengthenFail) (U1 p))

(GStrengthenS lw ls, GStrengthenS rw rs) => GStrengthenS (lw :*: rw :: k -> Type) (ls :*: rs :: k -> Type)

Strengthen product types by strengthening left and right.

This is ordered (left then right) in order to pass the field index along.

Defined in Strongweak.Generic.Strengthen

Methods

gstrengthenS :: forall (p :: k0). String -> String -> String -> String -> Natural -> (lw :*: rw) p -> (Natural, Validation (NonEmpty StrengthenFail) ((ls :*: rs) p))

(Strengthen s, Weak s ~ w, Selector mw, Selector ms) => GStrengthenS (S1 mw (Rec0 w) :: k -> Type) (S1 ms (Rec0 s) :: k -> Type)

Strengthen a field using the existing Strengthen instance.

Defined in Strongweak.Generic.Strengthen

Methods

gstrengthenS :: forall (p :: k0). String -> String -> String -> String -> Natural -> S1 mw (Rec0 w) p -> (Natural, Validation (NonEmpty StrengthenFail) (S1 ms (Rec0 s) p))

GStrengthenS (S1 mw (Rec0 w) :: k -> Type) (S1 ms (Rec0 w) :: k -> Type)

Special case: if source and target types are equal, copy the value through.

Defined in Strongweak.Generic.Strengthen

Methods

gstrengthenS :: forall (p :: k0). String -> String -> String -> String -> Natural -> S1 mw (Rec0 w) p -> (Natural, Validation (NonEmpty StrengthenFail) (S1 ms (Rec0 w) p))

selName'' :: forall s. Selector s => Maybe String

Get the record name for a selector if present.

On the type level, a 'Maybe Symbol' is stored for record names. But the reification is done using fromMaybe "". So we have to inspect the resulting string to determine whether the field uses record syntax or not. (Silly.)

conName' :: forall c. Constructor c => String

conName without the value (only used as a proxy). Lets us push our undefineds into one place.

datatypeName' :: forall d. Datatype d => String

datatypeName without the value (only used as a proxy). Lets us push our undefineds into one place.

selName' :: forall s. Selector s => String

selName without the value (only used as a proxy). Lets us push our undefineds into one place.