On 2 November 2010 14:10, Bertram Felgenhauer
bertram.felgenha...@googlemail.com wrote:
Indeed. I had a lot of fun with the ideas of this thread, extending
the 'Force' type family (which I call 'Eval' below) to a small EDSL
on the type level:
I also came up with this.. I was trying to use it
Max Bolingbroke wrote:
On 23 October 2010 15:32, Sjoerd Visscher sjo...@w3future.com wrote:
A little prettier (the cata detour wasn't needed after all):
data IdThunk a
type instance Force (IdThunk a) = a
Yes, this IdThunk is key - in my own implementation I called this Forced,
Hi Max,
neat idea! Haskell supports laziness even on the type level ;)
I tried to play with your code but did not get very far. I quickly ran
into two problems.
On Oct 22, 2010, at 7:37 PM, Max Bolingbroke wrote:
The annoying part of this exercise is the the presence of a Force in
the
On Oct 23, 2010, at 1:27 PM, Sebastian Fischer wrote:
I think `Control.Functor.Categorical.CFunctor` is a more natural replacement
for functor here. One can define
instance CFunctor (ListF a) ForceCat Hask
and I was hoping that I could define `fold` based on CFunctor but I did not
A little prettier (the cata detour wasn't needed after all):
data IdThunk a
type instance Force (IdThunk a) = a
type Alg f a = f (IdThunk a) - a
fold :: CFunctor f ForceCat (-) = Alg f a - Fix f - a
fold alg = alg . cmap (ForceCat $ fold alg)
sumAlg :: Alg (ListF Int) Int
On 23 October 2010 15:32, Sjoerd Visscher sjo...@w3future.com wrote:
A little prettier (the cata detour wasn't needed after all):
data IdThunk a
type instance Force (IdThunk a) = a
Yes, this IdThunk is key - in my own implementation I called this Forced, so:
type instance Force (Forced
I use Apply for Functor application in data-category, I used an infix operator
:%
http://hackage.haskell.org/packages/archive/data-category/0.3.0.1/doc/html/src/Data-Category-Functor.html#line-57
F.e. composition is defined like this:
type instance (g :.: h) :% a = g :% (h :% a)
Sjoerd
On
On Friday 22 October 2010 6:37:49 am Max Bolingbroke wrote:
This is all well and good, but it means when working with data types
defined in this manner you have to write Roll and unroll everywhere.
This is tedious :-(
Your discovery is interesting (and I haven't seen it before).
Another
