[Haskell-beginners] Re: Non-recursive binding expression

[Will Ness]

 <j.romildo <at> gmail.com> writes:

> 
> On Sat, Feb 28, 2009 at 01:01:56PM -0500, Brent Yorgey wrote:
> > On Sat, Feb 28, 2009 at 05:19:03PM +0000, Will Ness wrote:
> > >  <j.romildo <at> gmail.com> writes:
> > > 
> > > > Is there any non-recursive binding expression in Haskell?
> > > 
> > Assignment in Haskell is not destructive update.
> 
> I am not asking for assignment. What I want is indeed what I already
> said: a new lexical scope which introduces a new variable, but the
> variable name is being reused. That shadows the previous definition.
> 
> Romildo


The code I posted has exactly these semantics: 

When we write

  test = head $ 
    do xs <- [ [] ]
       xs <- [ 3:xs ]
       xs <- [ 8:xs ]
       xs <- [ 7:xs ]
       return xs

each xs in a singleton generator refers to its previous binding.