- July 7th, 2017:

In LU-decomposition of matrices you have square P-matrix:

[[1,0..],

[0,2,0..],

[0,0,3,0..],

...]

For matrices of n² size

Code that- ∃! David Turner @DaveCTurner
- matrix n = let td = take n . drop 1 in td [td $ replicate i 0 ++ [i] ++ repeat 0 | i <- [0..]]

# Typed Logic

Incorporates strong typing over predicate logic programming, and, conversely, incorporates predicate logic programming into strongly typed functional languages. The style of predicate logic is from Prolog; the strongly typed functional language is Haskell.

## Tuesday, August 1, 2017

### July 2017 1HaskellADay 1Liner

## Monday, July 31, 2017

### July 2017 1HaskellADay Problems and Solutions

- July 26th, 2017: We look at unifying fresh variables to ground terms for today's #haskell problem. And we have unification working for free variables and ground terms for today's #haskell solution.
- July 25th, 2017: We look at the beginnings of unification with ground terms for today's #haskell problem. Today's #haskell solution shows unification of ground terms in a monadic domain.
- July 24th, 2017: Commuters today occupy my mind for today's #haskell problem. A little reasoning, a little harsh reality, and we have today's #haskell solution.
- July 20th, 2017: I didn't go for my morning jog, so today's #haskell problem looks at running ... expressions. Eheh. For today's #haskell solution, some people run on empty, but I run on LOGIC! ... same thing.
- July 19th, 2017: Today's #haskell problem is our first step in our scheme to reasoning! MWA-HAHA! via the Reasoned Schemer. Today's #haskell solution:some days are #s; some days are #u

- July 7th, 2017: It's FRIDAY, and you know what that means? SCRABBLE DAY! for today's #haskell problem
- July 6th, 2017: For today's #haskell problem we invert a matrix to solve a system of equations.
- July 5th, 2017: For today's #haskell problem we have a * b = c ... HOW HARD CAN THAT BE? #famouslastwords The #haskell solution took like a whole second! THAT WAS HARD!
- July 4th, 2017: Boys and girls! Gather 'round as I spin you a story of Jemima and Roland for today's #haskell problem.
- July 3rd, 2017: Today's #haskell problem is all 'bout the Ord, 'bout the Ord, 'bout the Ord. No Functor. Today's #haskell solution uses a little sorting logic (not sordid logic; that's different) to show Jim is the eldest.

## Friday, July 7, 2017

### June 2017 1HaskellADay 1Liners

- June 17th, 2017:

f :: (a, [a]) -> [a] -> [a]

f (c, w1) w2 = c:w1 ++ w2

Define f points-free - bazzargh @bazzargh (++).uncurry(:)
- Felt there must be a nicer way to exploit symmetry of mappend.uncurry(mappend.pure) but can't find it

## Monday, July 3, 2017

### June 2017 1HaskellADay Problems and Solutions

- June 21st, 2017: Today's #haskell problem connects to and queries a SQL database of your choosing.
- June 16th, 2017: Today's #haskell problem has us interacting with the OS environment in anticipation of SQL database queries. Today's #haskell solution uses Applicative Functors to string together values we collect from the OS environment.
- June 15th, 2017: Today's Haskell problem comes by way of @aisamanra, Mr. Lists-are-Mu-functions-in-the-function-of-Mus. Today's #haskell solution shows Lists are Mu-functors! ... now, making them instances of type-classes, however ...
- June 14th, 2017: Today's #haskell problem is brought by way of @matthieubulte: approximating solutions with Runge-Kutta. The #haskell solution shows I can (ψ, ε, k) with the best of them! AHA! ... but is it the CORRECT solution? 🙄
- June 6th, 2017: In today's #haskell problem, we go clockwise around a binary tree, because ... we've had one too many?

## Friday, June 16, 2017

### May 2017 1Liners 1HaskellADay

- May 10th, 2017:

Define (^) :: (a -> a) -> Int -> (a -> a)

The 'power'-function where f ^ 3 = f . f . f - Conor McBride @pigworker flip ((ala Endo foldMap .) . replicate)

## Wednesday, June 7, 2017

### May 2017 1HaskellADay problems and solutions

- May 25th, 2017: Today's #haskell problem looks at the interconnectedness of languages as a graph.
- May 24th, 2017: Today's #haskell problem continues the exploration of spoken language roots catalogued in @wikidata. We present the first half of the #haskell solution that allows us to parse @wikidata results with optional values.
- May 23rd, 2017: I preface today's #haskell problem with a discussion on dirty/muddled data in @wikidata then continue onto languages. Today's #haskell solution shows us, e.g.: Cornish, Welsh and Breton are in the Brythonic language family. @wikidata
- May 22nd, 2017: Today's #haskell problem looks at spoken languages catalogued in @wikidata. Today's #haskell solution shows us @wikidata has NOTHING for the count of ENGLISH-speakers! #strangebuttrue
- May 17th, 2017: The NSA called. They are wanting the solution to today's #haskell Pentagon-number problem. Now.
- May 16th, 2017: Today's #haskell problem ... and Madonna! ... want you to justify my num! We find out that ALL YOUR BASE ARE BELONG TO US in today's #haskell solution
- May 15th, 2017: Today's #haskell problem warns us: "ACHTUNG, LOOKENPEEPERS! ZO RELAXEN UND WATSCHEN DER BLINKENLICHTEN." Today's #haskell solution taught me SO MUCH German. I mean SO MUCH!
- May 10th, 2017: For today's #haskell problem: when doing egg-arithmetic, we do not things by halves! ... or, perhaps, we do! Today's #haskell solution is EGGS! EGGS AS A POWER FUNCTION! EGGS EVERYWHERE!
- May 8th, 2017: Today's #haskell problem puts us 🎶 "Back on the Hang Gangs!" 🎶 Today's #haskell solution: "We must, indeed, all hang together or, most assuredly, we shall all hang separately."
- May 5th, 2017: HAPPY #CincodeMayo ... BUT ON A TUESDAY?!? What year was that, then? Today's #haskell problem. Today's #haskell solution shows Cinco de Mayo happens EVERY YEAR?!? Who da thunk it?
- May 3rd, 2017: Today's #haskell problem: April, May, and June are three sisters, and you have to find their ages. ... #awkward. Today's #haskell solution we have the old 1, 2, 3 sisters. Not that I'm saying these sisters are old. Not me. Nope.
- May 2nd, 2017: Ah! May! When Spring is in the Air! And #haskell-ers thoughts turn to Love* *solving today's problem. Today's #haskell solution presents a conundrum: Is the solution "spring" or "spring"? Hm. Tough call!
- May 1st, 2017: Happy May Day, #haskell-ers! Today we combat the academic illness: dafundzarlow ... let that sink in. Today we see two solutions to the #haskell problem of budgeting for cake and candy at Maura's school party. And to those of you who think #haskell has no practical application? Pooh on you! BUDGETING CAKE AND CANDY AT PARTIES IS TRÈS PRACTICAL! 😡

## Wednesday, May 10, 2017

### April 2017 1HaskellADay 1Liners

- April 14th, 2017: given

eitherOr, neitherNor :: Eq a => a -> a -> a -> Bool

Is eitherOr not neitherNor?

Prove or disprove. - April 14th, 2017: given

neitherNor :: Eq a => a -> a -> a -> Bool

andNot :: Eq a => a -> a -> Bool

How do you compose neitherNor 1 0 and andNot 4? - April 11th, 2017:

opts :: Credentials -> Options

opts c = defaults & auth ?~ basicAuth (pack $ keyToken c) (pack $ secretToken c)

point-free-itize

given:

data Credentials = Credentials { keyToken, secretToken :: String }

and (?~) and (&) are from Control.Lens

Snaps for elegance

The above code from quillio/Twillo.hs by ismailmustafa

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