[Haskell-cafe] Re: Total Functional Programming in Haskell

[apfelmus]

Jason Dagit wrote:
> Hello,
> 
> I recently had someone point me to this thread on LtU:
> http://lambda-the-ultimate.org/node/2003
> 
> The main paper in the article is this one:
> http://www.jucs.org/jucs_10_7/total_functional_programming/jucs_10_07_0751_0768_turner.pdf
> 
> It leaves me with several questions:
> 1) Are there are existing Haskell-ish implementations of the total
> functional paradigm?

Agda?

  http://appserv.cs.chalmers.se/users/ulfn/wiki/agda.php?n=Main.HomePage

It seems to me that dependent types are best for ensuring totality.

> 2) Could we restructure Haskell so that it comes in 3 layers, total
> functional core, lazy pure partial functional middle, and IO outer layer?

The IO layer can be interpreted as "co-total", i.e. as codata.
Basically, this means that it's guaranteed that the program prints or
reads something after a finite amount of time and does not loop forever
without doing anything.




Regards,
apfelmus