On 28 Aug 2008, at 8:34 am, Aaron Tomb wrote:
What type safety buys you, in my mind, is that Nothing is only a
valid value for explicit Maybe types. In cases where you don't use
Maybe, the "null" situation just can't occur. In languages with null
pointers, any pointer could possibly be null.
This is not true of Eiffel.
The ECMA Eiffel standard has
?T either a void reference or a reference to an instance of T
!T a reference to an instance of T
T same as !T in ECMA Eiffel; used to be same as ?T
I suppose you could call the detachable type ?T an *implicit* Maybe.
Needless to say, the switch in semantics of undecorated T helped to
fork the Eiffel community...
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