Language.Haskell.TH.DeepStrict

Check that a datatype is deeply strict, ie, it recursively only has strict fields.

DeepStrict

data DeepStrict reason

A type is deep strict if and only if for each constructor:

• All of its fields are strict, ie, they have a ! if possible.
• The type of of each field is deep strict.

The Monoid instance allows us to gather up reasons why a type fails to be deep strict.

Examples

() is deep strict because its single constructor doesn't have any fields so it is vacuously deep strict.

Int, Char, etc are all deep strict because they are wrappers around unlifted types that cannot be lazy.

Maybe Int is not deep strict. It has a Nothing constructor, which is fine. But, the Just constructor has a lazy field, which means it's not deep strict.

Constructors

DeepStrict

NotDeepStrict !reason

Instances

Functor DeepStrict

Defined in Language.Haskell.TH.DeepStrict

Methods

fmap :: (a -> b) -> DeepStrict a -> DeepStrict b

(<$) :: a -> DeepStrict b -> DeepStrict a

Lift reason => Lift (DeepStrict reason :: Type)

Defined in Language.Haskell.TH.DeepStrict

Methods

lift :: Quote m => DeepStrict reason -> m Exp

liftTyped :: forall (m :: Type -> Type). Quote m => DeepStrict reason -> Code m (DeepStrict reason)

Semigroup reason => Monoid (DeepStrict reason)

Defined in Language.Haskell.TH.DeepStrict

Methods

mempty :: DeepStrict reason

mappend :: DeepStrict reason -> DeepStrict reason -> DeepStrict reason

mconcat :: [DeepStrict reason] -> DeepStrict reason

Semigroup reason => Semigroup (DeepStrict reason)

Defined in Language.Haskell.TH.DeepStrict

Methods

(<>) :: DeepStrict reason -> DeepStrict reason -> DeepStrict reason

sconcat :: NonEmpty (DeepStrict reason) -> DeepStrict reason

stimes :: Integral b => b -> DeepStrict reason -> DeepStrict reason

Show reason => Show (DeepStrict reason)

Defined in Language.Haskell.TH.DeepStrict

Methods

showsPrec :: Int -> DeepStrict reason -> ShowS

show :: DeepStrict reason -> String

showList :: [DeepStrict reason] -> ShowS

Eq reason => Eq (DeepStrict reason)

Defined in Language.Haskell.TH.DeepStrict

Methods

(==) :: DeepStrict reason -> DeepStrict reason -> Bool

(/=) :: DeepStrict reason -> DeepStrict reason -> Bool

Ord reason => Ord (DeepStrict reason)

Defined in Language.Haskell.TH.DeepStrict

Methods

compare :: DeepStrict reason -> DeepStrict reason -> Ordering

(<) :: DeepStrict reason -> DeepStrict reason -> Bool

(<=) :: DeepStrict reason -> DeepStrict reason -> Bool

(>) :: DeepStrict reason -> DeepStrict reason -> Bool

(>=) :: DeepStrict reason -> DeepStrict reason -> Bool

max :: DeepStrict reason -> DeepStrict reason -> DeepStrict reason

min :: DeepStrict reason -> DeepStrict reason -> DeepStrict reason

Ppr reason => Ppr (DeepStrict reason)

Defined in Language.Haskell.TH.DeepStrict

Methods

ppr :: DeepStrict reason -> Doc

ppr_list :: [DeepStrict reason] -> Doc

data DeepStrictReason

Reasons why a type fails to be deep strict.

Constructors

LazyType !Type ![DeepStrictReason]

The type is lazy.

LazyConstructor !Name ![DeepStrictReason]

The type has a lazy constructor.

FieldReason !FieldKey ![DeepStrictReason]

One of the fields of the constructor fails to be deep strict.

LazyField !FieldKey

One of the fields of the constructor is lazy, ie, doesn't have a !.

LazyOther !String

Instances

Show DeepStrictReason

Defined in Language.Haskell.TH.DeepStrict

Methods

showsPrec :: Int -> DeepStrictReason -> ShowS

show :: DeepStrictReason -> String

showList :: [DeepStrictReason] -> ShowS

Eq DeepStrictReason

Defined in Language.Haskell.TH.DeepStrict

Methods

(==) :: DeepStrictReason -> DeepStrictReason -> Bool

(/=) :: DeepStrictReason -> DeepStrictReason -> Bool

Ord DeepStrictReason

Defined in Language.Haskell.TH.DeepStrict

Methods

compare :: DeepStrictReason -> DeepStrictReason -> Ordering

(<) :: DeepStrictReason -> DeepStrictReason -> Bool

(<=) :: DeepStrictReason -> DeepStrictReason -> Bool

(>) :: DeepStrictReason -> DeepStrictReason -> Bool

(>=) :: DeepStrictReason -> DeepStrictReason -> Bool

max :: DeepStrictReason -> DeepStrictReason -> DeepStrictReason

min :: DeepStrictReason -> DeepStrictReason -> DeepStrictReason

Ppr DeepStrictReason

Defined in Language.Haskell.TH.DeepStrict

Methods

ppr :: DeepStrictReason -> Doc

ppr_list :: [DeepStrictReason] -> Doc

Lift DeepStrictReason

Defined in Language.Haskell.TH.DeepStrict

Methods

lift :: Quote m => DeepStrictReason -> m Exp

liftTyped :: forall (m :: Type -> Type). Quote m => DeepStrictReason -> Code m DeepStrictReason

type DeepStrictWithReason = DeepStrict [DeepStrictReason]

Checking data types

isDeepStrict :: Type -> Q DeepStrictWithReason

Determine if a type is deep strict Invariant: The type doesn't contain any free variables, eg, Maybe a will fail.

isDeepStrictWith :: Context -> Type -> Q DeepStrictWithReason

assertDeepStrict :: Type -> Q [Dec]

Assert that a type is deep strict. If the type isn't deep strict then this will produce an error with the reasons why.

assertDeepStrictWith :: Context -> Type -> Q [Dec]

Context

data Context

Allow overriding various setting that determine what types we consider deep strict.

Constructors

Context

Fields

• contextSpine :: !(Set Type)

  The types we are recursively checking. By the inductive hypothesis, we assume they are DeepStrict.

• contextCache :: !(IORef (Map Type DeepStrictWithReason))
• contextOverride :: !(Map Name (Maybe [Strictness]))

  Maps names of types to whether they can be deep strict and if they can which arguments need to be strict

• contextRecursionDepth :: !Int

  A recursion depth to avoid infinite loops.

data Strictness

Whether a type is used strictly by a data type. We use these to annotate types with deep strictness overrides. Types that have fields labelled as Strict require those types to be deep strict. Types that have fields labelled as Lazy will never be deep strict, but this can be helpful for nicer messages.

Constructors

Strict

Lazy

Instances

Show Strictness

Defined in Language.Haskell.TH.DeepStrict

Methods

showsPrec :: Int -> Strictness -> ShowS

show :: Strictness -> String

showList :: [Strictness] -> ShowS

Eq Strictness

Defined in Language.Haskell.TH.DeepStrict

Methods

(==) :: Strictness -> Strictness -> Bool

(/=) :: Strictness -> Strictness -> Bool

Ord Strictness

Defined in Language.Haskell.TH.DeepStrict

Methods

compare :: Strictness -> Strictness -> Ordering

(<) :: Strictness -> Strictness -> Bool

(<=) :: Strictness -> Strictness -> Bool

(>) :: Strictness -> Strictness -> Bool

(>=) :: Strictness -> Strictness -> Bool

max :: Strictness -> Strictness -> Strictness

min :: Strictness -> Strictness -> Strictness

emptyContext :: Q Context

The default Context.

type FieldKey = Either Int Name