[Haskell-cafe] What is your favourite Haskell "aha" moment?

[Jerzy Karczmarczuk]

My goodness...
Neither Simon, nor the five  responders ever mention *laziness*!

For me it was THE "aha" moment, or rather a long period...

The problem with popularizing laziness is that too many short comments 
(on Internet) on it are not serious. People speak mainly about infinite 
lists (as if somebody really cared about this "infinity"), or that lazy 
program do not evaluate some expressions, which should *economise* some 
time, which usually is not true...

*

For me, lazy programs permit to represent dynamic processes as data.

Iterations as mathematical structures.

Co-recursive perturbational schemes (or asymptotic expansions, etc.), 
which are 10 or more times shorter than the orthodox approaches, and 
remain readable, and natural.

Laziness makes it possible to play with continuations, thus: "making 
future explicit",  in a particularly constructive manner.

===========================

Second section...

Somebody mentioned "type families".

Why not, but for an audience outside of the FP realm??
If something about types, then for sure the automatic polymorphic 
inference, which remains a bit mysterious for many people, including my 
(comp. sci.) students. And the /*Curry-Howard correspondence*/.

All the best.


Jerzy Karczmarczuk

/Caen, France/




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