Week 4: if you have read this and you have no questions, please close this issue.

[BertLisser]

Opg 5

-- Haskell has built in isTransitive
-- isTransitive r = and [((x `po` y) && (y `po` z)) `implies` (x `po` z) | x <- set, y <- set, z <- set]
--testTrClos1 = isTransitive (trClos [(1,1), (1,2), (1,3), (2,3), (3,1)])

Where do you find this en why didn't you use this? However the definition of isTransitive is very nice.

Opg 4

trClos :: Ord a => Rel a -> Rel a
trClos r = nub (trClosHelper (trClosHelper r))

trClosHelper :: Ord a => Rel a -> Rel a
trClosHelper [] = []
trClosHelper (x:xs) = x : ([x] @@ xs) ++ trClos xs

is OK, but the definition can be shorter and more optimal (even an one liner).

[Tessmore]

Hello BertLisser,

All built in Haskell functions can be found in the documentation: For example: http://hackage.haskell.org/package/HaskellForMaths-0.4.5/docs/src/Math-Combinatorics-Poset.html#isTransitive

For the trClosHelper, since we use the @@ it could never be a one-liner right? As that is already 3 lines on its own. Or what exactly do you mean?

[BertLisser]

All built in Haskell functions can be found in the documentation: For example: http://hackage.haskell.org/package/HaskellForMaths-0.4.5/docs/src/Math-Combinatorics-Poset.html#isTransitive Thank you for the tip. But why didn't you use this. For the trClosHelper, since we use the @@ it could never be a one-liner right? As that is already 3 lines on its own. Or what exactly do you mean?

I mean for example this: trClos :: Ord a => Rel a -> Rel a trClos x = lfp (\ x -> nub (x ++ (x @@ x))) x

I admit that this solution requires a lot of experience in functional programming.

Kind Regards

   Bert

----- Original Message ----- From: "Tessmore" notifications@github.com To: "Tessmore/gr_v4" gr_v4@noreply.github.com Cc: "BertLisser" Bert.Lisser@cwi.nl Sent: Saturday, October 5, 2013 5:45:15 PM Subject: Re: [gr_v4] Week 4: if you have read this and you have no questions, please close this issue. (#1)

Hello BertLisser,

For the trClosHelper, since we use the @@ it could never be a one-liner right? As that is already 3 lines on its own. Or what exactly do you mean?

---

Reply to this email directly or view it on GitHub: https://github.com/Tessmore/gr_v4/issues/1#issuecomment-25750846

[Tessmore]

Thanks. I will look into it!