Bulat Ziganshin wrote:
ok, i can live without it. i mean reasoning :)
i guess that anything more complex than Turing machine makes reasoning harder. 18 years ago Haskell fathers chosen to simpilfy language in order to make reasoning easier. may be now we can change this decision? that i've proposed is made on basis of my 15 years of software development experience and i'm sure that abstraction of data representation is very important issue (and much more important than reasoning for practical programming)
No. Abstractions should (and mostly do) make reasoning easier, not harder, by having clear semantics, suited to the problem domain. The ability to reason about your program is vital in about every part of the programming cycle, and is one of the things that make Haskell work. Another of those things is abstraction of data representation, you're right about that. But I think there is no conflict between those goals. In fact, all the views proposal does is to give the natural meaning to the equation
f (v x) = h x
, by letting the programmer specify a partial inverse for 'v'. Greetings, Arie