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

[erik]

For me there were two important "aha" moments. Right at the beginning I was
drawn in by using ADTs and pattern-matching on them. It's so simple and
plain and now it's the first thing I miss in any other language I have to
work with. I feel like this would make a short, compelling example for
programmers coming from any other background.

The second was reading Wadler's "Monads for Functional Progamming" (and
reading it a second and third time, if we're being honest). The ways in
which he takes three seemingly disconnected examples and reduces them to
this broader mathematical abstraction: I found it quite beautiful and
surprising once I fully appreciated it.


On Wed, Jul 11, 2018 at 7:29 AM Ionuț G. Stan <ionut.g.stan at gmail.com>
wrote:

> This is not necessarily related to Haskell, as I've had this A-HA moment
> while watching the 1984 SIPC lectures from MIT.
>
> Anyway, at some point, Mr Sussman (or was it Mr Abelson?) used `+` as an
> argument to another function. I was bedazzled!
>
> First of all, it was the syntactic novelty — `+` was not some rigid part
> of the syntax, it was just a name — secondly, it was not any name, it
> was the name of a *function*  that was sent to another function. It was
> probably my first encounter with higher-order functions.
>
> If I remember correctly, the code was along the lines of:
>
> foldl (+) 0 [1,2,3]
>
>
> On 11/07/2018 15:10, Simon Peyton Jones via Haskell-Cafe wrote:
> > Friends
> >
> > In a few weeks I’m giving a talk to a bunch of genomics folk at the
> > Sanger Institute <https://www.sanger.ac.uk/> about Haskell.   They do
> > lots of programming, but they aren’t computer scientists.
> >
> > I can tell them plenty about Haskell, but I’m ill-equipped to answer the
> > main question in their minds: /why should I even care about Haskell/?
> > I’m too much of a biased witness.
> >
> > So I thought I’d ask you for help.  War stories perhaps – how using
> > Haskell worked (or didn’t) for you.  But rather than talk generalities,
> > I’d love to illustrate with copious examples of beautiful code.
> >
> >   * Can you identify a few lines of Haskell that best characterise what
> >     you think makes Haskell distinctively worth caring about?
> >     Something that gave you an “aha” moment, or that feeling of joy when
> >     you truly make sense of something for the first time.
> >
> > The challenge is, of course, that this audience will know no Haskell, so
> > muttering about Cartesian Closed Categories isn’t going to do it for
> > them.  I need examples that I can present in 5 minutes, without needing
> > a long setup.
> >
> > To take a very basic example, consider Quicksort using list
> > comprehensions, compared with its equivalent in C.  It’s so short, so
> > obviously right, whereas doing the right thing with in-place update in C
> > notoriously prone to fencepost errors etc.  But it also makes much less
> > good use of memory, and is likely to run slower.  I think I can do that
> > in 5 minutes.
> >
> > Another thing that I think comes over easily is the ability to abstract:
> > generalising sum and product to fold by abstracting out a functional
> > argument; generalising at the type level by polymorphism, including
> > polymorphism over higher-kinded type constructors.   Maybe 8 minutes.
> >
> > But you will have more and better ideas, and (crucially) ideas that are
> > more credibly grounded in the day to day reality of writing programs
> > that get work done.
> >
> > Pointers to your favourite blog posts would be another avenue.  (I love
> > the Haskell Weekly News.)
> >
> > Finally, I know that some of you use Haskell specifically for genomics
> > work, and maybe some of your insights would be particularly relevant for
> > the Sanger audience.
> >
> > Thank you!  Perhaps your responses on this thread (if any) may be
> > helpful to more than just me.
> >
> > Simon
> >
> >
> >
> > _______________________________________________
> > Haskell-Cafe mailing list
> > To (un)subscribe, modify options or view archives go to:
> > http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
> > Only members subscribed via the mailman list are allowed to post.
> >
>
>
> --
> Ionuț G. Stan  |  http://igstan.ro  |  http://bucharestfp.ro
> _______________________________________________
> Haskell-Cafe mailing list
> To (un)subscribe, modify options or view archives go to:
> http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
> Only members subscribed via the mailman list are allowed to post.



-- 
Erik Aker
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/haskell-cafe/attachments/20180711/4413fc47/attachment.html>