[Haskell-cafe] Haskell Propeganda
Richard A. O'Keefe
ok at cs.otago.ac.nz
Wed Aug 27 21:46:41 EDT 2008
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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