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Julie Moronuki: Introduction to Monoids
Bay Area Haskell
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- Recommended by 1 person: 1 in engineering communities.
- Presented by Julie Moronuki
- Linked in the descriptionGinBaby/talks
Beginner. No background in the topic needed.
2.8K views9 years ago1 recommendation
Programming languagesComputer scienceHaskellFunctional programming
Julie Moronuki introduces the mathematical and programming concepts of monoids and semigroups using Haskell.
Presented at BayHac 2017 wiki.haskell.org/BayHac2017 Outline: github.com/GinBaby/talks/blob/master/semigroups.md Applicatives are Monoidal argumatronic.com/posts/2017-03-08-applicative-instances.htmlWhy it's here
1 person recommends thisWhat people say. Recommended as a very clear and accessible introduction to monoids for beginners.
u/Iceland_jackin r/haskell • Mentions
On “BayHac 2017 recordings”
Julie's long awaited monoid/semigroup talk :)
`minimum` (as discussed) doesn't quite belong in `Foldable` but rather `Foldable1` (subclass of `Foldable` for non-empty structures):
-- Data.Foldable
class Foldable (t :: Type -> Type) where
fold :: Monoid m => t m -> m
foldMap :: Monoid m => (a -> m) -> (t a -> m)
-- Data.Semigroup.Foldable
class Foldable t => Foldable1 (t :: Type -> Type) where
fold1 :: Semigroup m => t m -> m
foldMap1 :: Semigroup m => (a -> m) -> (t a -> m)
Using `foldMap1` we can define a `minimum1` that cannot be applied to empty structures
{-# Language InstanceSigs #-}
newtype Min a = Min { getMin :: a }…