Fallback value will be returned when invalid input is provided:
type = Dry::Types['integer'].fallback(100)
type.call(99) # => 99
type.call('99') # => 100
type.call(:invalid) # => 100
Block syntax:
cnt = 0
type = Dry::Types['integer'].fallback { cnt += 1 }
type.call(99) # => 99
type.call('99') # => 1
type.call(:invalid) # => 2
Fallbacks are different from default values because the latter are triggered on missing input rather than invalid. They can be combined:
schema = Dry::Types['hash'].schema(
size: Dry::Types['integer'].fallback(50).default(100)
)
schema.call({}) # => { size: 100 }
schema.call({ size: 'invalid' }) # => { size: 50 }