Ertugul,
I admire your passion for rigor and discipline. It is not natural for
me but I am slowly coming to the same place.

I also feel that Haskell development is like learning to play music.
I've seen many a student (myself included) turn away from an
instrument because of an over-emphasis on scales, arpeggios etc. and
less on playing what sounds good. It is true that eventually to play
seriously some understanding of that theory is required but the
musician will come to that conclusion on their own.

They will hear a pattern over and over and wonder if it has a name -
then you show them the major scale and it will all make sense because
it will be a solution to a problem, not a solution waiting for a
problem.

In some ways I feel that the Haskell community because of their
expertise and enthusiasm gives users answers to questions they haven't
asked yet. When they do (inevitably) ask your awesome monad tutorial
(which helped me a great deal) will be there.

-deech

On Sat, Jul 23, 2011 at 6:39 PM, Ertugrul Soeylemez <es@ertes.de> wrote:

David Place <d@vidplace.com> wrote:

Point taken, but to get serious with Haskell you will want to learn

applicative functors and at least the function arrow anyway.

Interesting thoughts, Ertugrul.  I would argue that you can get very

serious with Haskell without understanding applicative functors and

the function arrow.  The very basic aspects of the language (the type

system, higher-order functions, lazy evaluation, etc…) are already so

powerful, that you really don't need to add complexity to simple

programs by including some of the more obscure extensions.  I could

see if it made the code substantially more compact.  In this case, it

makes the code more verbose as you need to import the two modules to

do something which can be so trivially expressed as an abstraction.

Haskell application development is more than just the language.  The

language itself is very powerful, yes, but serious applications I write

usually have quite a few dependencies.  If you want to reinvent the

wheel for everything, then yes, I'm exaggerating.  Personally I don't

want to, because there are great libraries and design patterns out

there, for which you simply need to understand more than just the

language.

It's as simple as this:  To get serious with Haskell, you need to

understand Haskell monads.  Understanding them implies understanding

applicative functors (not necessarily the applicative style).  For many

of the useful libraries you will want to go further and understand monad

transformers and more.

I'm not talking about any ideals here.  I'm talking about real world

application development, which is what I am doing.

When you write a program, do you think of it as a document only for

the compiler to understand, or might some other people need to

understand it someday?

"It"?  For me type signatures are specification for the compiler and

documentation for humans, along with Haddock-style comments.  My code is

usually very well documented.  In most cases Haddock shows me a coverage

of 100% for all of my source files, and every top-level and

'where'-definition has a type signature.  I'm very rigorous here.

All of the power I get from Haskell itself, the base library and the

many libraries I use I view as tools to get stuff done quickly, safely

and elegantly.  As said, there is always a simpler way to write stuff,

but I have a certain style, which I follow consistently, and in that

style I write 'second pure'.  That's it.

Why not '(:[])'?  Simply because I hate it and find it confusing.  Why

not 'return'?  Because I write my code reasonably general.  Not that

using 'return' would change the type signature in question, but it is

just my style.  In a do-block I use 'return'.  Everywhere else I use

'pure'.  Consistently.  Why 'second'?  Because it's convenient.

Greets,

Ertugrul

--

nightmare = unsafePerformIO (getWrongWife >>= sex)

http://ertes.de/

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