i like the example

but you say yourself it just means that bar2 should be elsewhere.::?

ie an oo'er would just say youve created the wrong abstraction, but not....dont create the abstraction....creating the abstraction is the mantra oo'ers are stylistically indoctonated in, in the name of extensibility (for good or evil)

so...is the problem with type classes that this modelling process is quite subtle and advanced? and thus should be avoided until you know what you're doing?

or something more?

(maybe the cost of the modelling process outweighs the benefit? even when you do know what youre doing?)

Excuse the spelling, sent from a phone with itty bitty keys, it like trying to sow a button on a shirt with a sausage.

On 3 Nov 2016, at 20:20, Brandon Allbery <allbery.b@gmail.com> wrote:

On Thu, Nov 3, 2016 at 4:47 AM, Nicholls, Mark <nicholls.mark@vimn.com> wrote:

i believe there is advice to avoid typeclasses stylistically? (see haskell wiki on style, allegedly because it leads to creeping haskell extensions...overlapping instances etc)...which lead you into the "wild" (allegedly SPJ)

Typeclasses are great when used properly and for their intended purpose. There is a tendency for new Haskellers to overuse them, or to mistake them for OOP classes and try to use them as such (which won't work, but *will* cause the compiler to start suggesting increasingly-far-afield extensions as it tries to make sense of what the programmer was trying to do).

--

brandon s allbery kf8nh sine nomine associates

allbery.b@gmail.com ballbery@sinenomine.net

unix, openafs, kerberos, infrastructure, xmonad http://sinenomine.net

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