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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Seeking for papers about tagged types vs access to subprograms
Date: Sat, 11 May 2013 11:08:51 +0200
Organization: cbb software GmbH
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Date: 2013-05-11T11:08:51+02:00
List-Id: <comp.lang.ada>

On Sat, 11 May 2013 09:58:38 +0200, Yannick Duch�ne (Hibou57) wrote:

> Le Sat, 11 May 2013 08:37:15 +0200, Dmitry A. Kazakov  
> <mailbox@dmitry-kazakov.de> a �crit:
>> That applies to stateful types only. Not every type is stateful. Bringing
>> state into objects is considered bad practice. So bad, that it motivated
>> some people to invent whole programming paradigms to avoid stateful object,
>> e.g. functional programming. The sole idea of FP is to sweep states under
>> the carpet.
> 
> FP is about expression without side effects (pure expression), not about  
> refusing to express states.

Side effect here = object[s] state.

[You certainly cannot attribute it to the control flow state as you return
to the definite point after expression is computed.]

> There is no issue to have expressions  
> representing states and functions returning a state from a state,

You return values not states. State of the object is the value it presently
represents. State of flow is the source code location.

> I've never seen so far, a paper about avoiding states in FP (what would be  
> state in FP anywhere, it not defined by the domain?). Else, out of  
> curiosity, I would welcome a pointer.

FP-guys usually refuse to mention objects for evident reasons.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de