Just for the heck of it, I tried out an implementation of scanl using
Joachim Breitner's magical oneShot primitive. Using the test
scanlA :: (b - a - b) - b - [a] - [b]
scanlA f a bs = build $ \c n -
a `c`
foldr (\b g x - let b' = f x b in (b' `c` g b'))
(const n)
bs
Wait, isn't call arity analysis meant to do this by itself now?
On 7 October 2014 17:05, David Feuer david.fe...@gmail.com wrote:
Just for the heck of it, I tried out an implementation of scanl using
Joachim Breitner's magical oneShot primitive. Using the test
scanlA :: (b - a - b) - b - [a]
Yes, and it does a very good job in many cases. In other cases, it's
not as good.
On Tue, Oct 7, 2014 at 7:59 AM, Sophie Taylor sop...@traumapony.org wrote:
Wait, isn't call arity analysis meant to do this by itself now?
On 7 October 2014 17:05, David Feuer david.fe...@gmail.com wrote:
Just
On Sep 12, 2014 2:35 PM, Joachim Breitner m...@joachim-breitner.de
wrote:
I once experimented with a magic oneShot :: (a - b) - (a - b)
function, semantically the identity, but tell the compiler not to share
the result of the computation. Using that in the definition of
foldl-as-foldr, one can
Hi,
Am Mittwoch, den 24.09.2014, 16:37 -0400 schrieb David Feuer:
On Sep 12, 2014 2:35 PM, Joachim Breitner m...@joachim-breitner.de
wrote:
I once experimented with a magic oneShot :: (a - b) - (a - b)
function, semantically the identity, but tell the compiler not to
share
the result of
Joachim Breitner wrote:
Am Samstag, den 13.09.2014, 00:01 -0400 schrieb David Feuer:
On Sep 12, 2014 2:35 PM, Joachim Breitner m...@joachim-breitner.de
wrote:
Interesting. I assumed that some wrap.unwrap=id law would hold, or
at
least some moral approximation (e.g. disregarding
Which scanl wrapper are you referring to?
The first one I figured out was quite wrong in certain ways. But I think
the new one is less controversial; it's a lot like the reverse one.
On Sun, Sep 14, 2014 at 1:03 PM, David Feuer david.fe...@gmail.com wrote:
Joachim Breitner wrote:
Am Samstag,
Your scanl wrapper might be right for scanl, but it does not satisfy the
condition Joachim proposed. In particular, if we define
(!!) :: [a] - Int - a
xs !! n
| n 0 = error Negative index.
| otherwise = foldrW indexWrap indexCons (error Large index.) xs n
where
indexCons x _ 0 = x
Hi,
Am Sonntag, den 14.09.2014, 14:47 -0400 schrieb David Feuer:
Your scanl wrapper might be right for scanl, but it does not satisfy
the condition Joachim proposed. In particular, if we define
(!!) :: [a] - Int - a
xs !! n
| n 0 = error Negative index.
| otherwise = foldrW
Hi,
Am Samstag, den 13.09.2014, 00:01 -0400 schrieb David Feuer:
On Sep 12, 2014 2:35 PM, Joachim Breitner m...@joachim-breitner.de
wrote:
Interesting. I assumed that some wrap.unwrap=id law would hold, or
at
least some moral approximation (e.g. disregarding bottoms in an
acceptable
On Sep 12, 2014 2:35 PM, Joachim Breitner m...@joachim-breitner.de
wrote:
Interesting. I assumed that some wrap.unwrap=id law would hold, or at
least some moral approximation (e.g. disregarding bottoms in an
acceptable manner). But if the wrappers have to do arbitrary stuff that
can
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