Safe Haskell | None |
---|---|
Language | Haskell2010 |
Documentation
class From source target where Source #
This type class is for converting values from some source
type into
some other target
type. The constraint
means that
you can convert from a value of type From
source targetsource
into a value of type
target
.
This type class is for conversions that cannot fail. If your conversion can
fail, consider implementing TryFrom
instead.
Nothing
from :: source -> target Source #
This method implements the conversion of a value between types. At call
sites you will usually want to use into
instead of this method.
The default implementation of this method simply calls coerce
,
which works for types that have the same runtime representation. This
means that for newtype
s you do not need to implement this method at
all. For example:
>>>
newtype Name = Name String
>>>
instance 'From' Name String
>>>
instance 'From' String Name