- January 8th, 2018: from Nicoλas @BeRewt

A small @1HaskellADay, old-school. Define foo:

> foo 3 [1..5]

[([1,2,3], 4), ([2,3,4], 5)]

> foo 2 [1..4]

[([1,2], 3), ([2,3], 4)]

> foo 2 [1..20]

[([1,2],3), ([2,3],4), ..., ([18,19],20)]

> foo 20 [1..2]

[] - Demiurge With a Teletype @mrkgrnao

foo n

= tails

# filter (length # (> n))

# map (splitAt n # second head)

(#) = flip (.) - Andreas Källberg @Anka213

I haven't tested it, but this should work:

foo n xs = [ (hd,x) | (hd , x:_) <- n="" splitat=""> tails xs ] - <- n="" splitat="">Nicoλas @BeRewt foo n = zip <$> fmap (take n) . tails <*> drop n
- January 5th, 2018: You have the following DAG-paths:

a -> b -> c -> e

a -> b -> d -> e

q -> r -> s

w -> x

y -> z

and many more.

From a path, provide a bi-directional encoding* given maximum graph depth is, say, 7, max number of roots is, say, 10, and max number of nodes is, say, 1000. - *bi-directional encoding of a graph path:

DAG path -> enc is unique for an unique DAG path

enc -> DAG path yields the same DAG path that created the unique enc.

*DAG: "Directed, acyclic graph." - January 5th, 2018: given s :: Ord k => a -> (k,[v])

define f using s

f :: Ord k => [a] -> Map k [v]

with no duplicate k in [a] - Christian Bay @the_greenbourne f = foldr (\e acc -> uncurry M.insert (s e) acc) M.empty
- me: you can curry away the acc variable easily
- Christian Bay @the_greenbourne You're right :)

f = foldr (uncurry M.insert . s) M.empty - Bazzargh @bazzargh fromList.(map s) ?
- me: Yuppers

## Tuesday, February 6, 2018

### January 2018 1Liner 1HaskellADay problems and solutions

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