[Haskell-cafe] Haskell & monads for newbies

Andrew Coppin andrewcoppin at btinternet.com
Sat Jul 14 15:02:23 EDT 2007

Hugh Perkins wrote:
> On 7/14/07, *Andrew Coppin* <andrewcoppin wrote:
> > That is my recollection also. (Don't ask me *which* monads, mind you...)
> In the case in point, the law breakage never the less matches
> "intuition"; personally, I ignore the monad laws on the basis that if
> you're doing something "sane", the laws will automatically hold anyway.
> (But maybe I'm just a renegade?)
> Yeah, the laws confused me for a while as well.  Hint to guys writing 
> Haskell documentation, we're not all doing CS phD you know ;-)  We 
> just want to get things done ;-)
> Andrew, I found comfort and explanation in this article 
> http://www.haskell.org/haskellwiki/Monads_as_containers :
> "The functions return and bind need to satisfy a few laws 
> <http://www.nomaware.com/monads/html/laws.html#laws> in order to make 
> a monad, but if you define them in a sensible way given what they are 
> supposed to do, the laws will work out. The laws are only a formal way 
> to give the informal description of the meanings of return and bind I 
> have here."

Oh, I *understand* the laws - I just think that if you're trying to 
explain how to *use* (not *write*) monads, you really don't need to 
emphasize this "laws" business. IMHO...

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