[Haskell-cafe] Comments from OCaml Hacker Brian Hurt

Philippa Cowderoy flippa at flippac.org
Fri Jan 16 08:46:25 EST 2009

On Fri, 16 Jan 2009, Duncan Coutts wrote:

> If you or anyone else has further concrete suggestions / improvements
> then post them here now! :-)

Spell out what associativity means and what it means for that operation to 
have an identity. List a few examples (stating that they're not all 
instances), including the * and + ones for arithmetic (use this to explain 
the issue with multiple monoids existing on one type, possibly use it to 
mention newtypes and newtype deriving as a workaround). Mention the 
intuition of monoids as abstract 'sequences', in which the sequence itself 
may be hidden after evaluation or be irrelevant because the operation 
commutes - the two arithmetic monoids are a good example in both cases.

Bonus points for explaining the relationship between monoids and folds 

flippa at flippac.org

'In Ankh-Morpork even the shit have a street to itself...
 Truly this is a land of opportunity.' - Detritus, Men at Arms

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