Infinitely nested containers

Rustom Mody rustompmody at gmail.com
Sat Nov 22 07:03:26 CET 2014


On Saturday, November 22, 2014 10:40:23 AM UTC+5:30, Chris Angelico wrote:
> On Sat, Nov 22, 2014 at 4:02 PM, Rustom Mody  wrote:
> > Thats not a single expression; which is possible with a lazy
> > evaluation language like Haskell.
> > Prelude> let ones = 1 : ones
> 
> I'm not sure "lazy evaluation" is the key here, unless it also does
> name lookups lazily. What happens if you do this:
> 
> let foo = 1 : bar
> let bar = 2 : 3
> foo
> 
> Will that show 1, 2, 3? If so, then sure, lazy eval is what achieved
> that - but it's also going to make it hard to track down name errors.

Prelude> let foo = 1 : bar; bar = 2 : [3]
Prelude> foo
[1,2,3]


Prelude> let foo = 1 : bar; bar = 2 : foo
Prelude> foo
[1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1,2,1 <Control-C>



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