Numeric.Units.Dimensional.Coercion

The function coerce allows you to safely convert between values of types that have the same representation with no run-time overhead. In the simplest case you can use it instead of a newtype constructor, to go from the newtype's concrete type to the abstract type. But it also works in more complicated settings, e.g. converting a list of newtypes to a list of concrete types.

When used in conversions involving a newtype wrapper, make sure the newtype constructor is in scope.

This function is representation-polymorphic, but the RuntimeRep type argument is marked as Inferred, meaning that it is not available for visible type application. This means the typechecker will accept coerce @Int @Age 42.

Examples

>>> newtype TTL = TTL Int deriving (Eq, Ord, Show)>>> newtype Age = Age Int deriving (Eq, Ord, Show)>>> coerce (Age 42) :: TTLTTL 42>>> coerce (+ (1 :: Int)) (Age 42) :: TTLTTL 43>>> coerce (map (+ (1 :: Int))) [Age 42, Age 24] :: [TTL][TTL 43,TTL 25]

A dimensional value, either a Quantity or a Unit, parameterized by its Dimension and representation.

Unwraps a possibly-scaled SQuantity, yielding its underlying representation.

This is a type-restricted version of coerce.