[Haskell-cafe] Haskell Propeganda

wren ng thornton wren at freegeek.org
Fri Aug 29 04:57:14 EDT 2008

Richard A. O'Keefe wrote:
> 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...

Just because the devil needs more advocacy... there are safer dialects 
of C that have non-nullable pointers in addition to the standard 
variety. Cyclone[1] comes to mind, there are others.

In so far as propaganda goes, imperative programming is ugly, unsafe, 
and evil, but it is getting better. Blanket statements about their 
failings tend toward falsity as they keep adopting things from the 
functional world.

[1] http://www.cs.bu.edu/groups/ibench/presentations/2003-04-10.pdf

Live well,

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