On 22.07.2013 10:50, MigMit wrote:
On Jul 22, 2013, at 12:27 PM, Andreas Abel <andreas.a...@ifi.lmu.de>
wrote:
On 20.07.13 9:36 PM, Evan Laforge wrote:
However, I'm also not agitating for a non-recursive let, I think
that ship has sailed. Besides, if it were added people would
start wondering about non-recursive where, and it would introduce
an exception to haskell's pretty consistently order-independent
declaration style.
For functions, recursive-by-default let makes sense. But for
*values*, intended recursion is rather the exception. It is useful
for infinite lists and the like. For values of atomic type like
Int or Bool, recursive let is a bug.
It seems hard to distinguish between them. What about values that
contain functions, like data T = T Int (Int -> Int)? What about
polymorphic values, that could be functions and could be not?
I agree. It cannot be implemented like that. A thing that could be
implemented is that
let x = e
is an error if x appears strictly in e. In practice, this could catch
some unintended cases of recursion like
let x = x +1
, but not all of them.
Cheers,
Andreas
--
Andreas Abel <>< Du bist der geliebte Mensch.
Theoretical Computer Science, University of Munich
Oettingenstr. 67, D-80538 Munich, GERMANY
andreas.a...@ifi.lmu.de
http://www2.tcs.ifi.lmu.de/~abel/
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