Re: [9fans] nice quote

[James Chapman <james@cs.ioc.ee>]

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On Sep 6, 2009, at 9:05 PM, David Leimbach wrote:
> On Sun, Sep 6, 2009 at 10:08 AM, Eris Discordia <eris.discordia@gmail.com
> > wrote:
> In this respect rating the "expressive power of C versus LISP" depends
> very much on the problem domain under discussion.
>
> Of course. I pointed out in my first post on the thread that "[...]
> for a person of my (low) caliber, LISP is neither suited to the
> family of problems I encounter nor suited to the machines I solve
> them on." I cannot exclude other machines and other problems but can
> talk from what little I have personally experienced.
>
> I would like to see Haskell fill C's niche [...]
>
> Is it as readily comprehensible to newcomers as C? Are there texts
> out there that can welcome a real beginner in programming and help
> him become productive, on a personal level at least, as rapidly as
> good C textbooks--you know the classic example--do? Is there a
> coherent mental model of small computers--not necessarily what you
> or I deem to be a small computer--that Haskell fits well and can be
> taught to learners? I imagine those will be indispensable for any
> language to replace existing languages, much more so in case of C.
>
> According to the designer of F# (another functional programming
> language that takes it's syntax from O'Caml as well as Haskell and
> even Python), one of the best experiences he'd had was working with
> a high school student who was able to modify a solar system
> simulation written in F# with no prior programming experience.
> (from http://www.computerworld.com.au/article/271034/)
>
> There's books on F# out there, and F# for Scientists.
>
> http://www.ffconsultancy.com/products/fsharp_for_scientists/index.html
>
> There's books on multimedia programming in Haskell out there that
> also attempt to show programming to newcomers, but I'm not sure any
> of them really assume no prior programming experience.
>
> I think people learning C get one view of the computer that folks
> learning assembly really learn to appreciate :-).  Folks learning
> Haskell learn another mental model of programming as well.
>
> My personal belief is that learning new languages makes one think
> about the languages they are used to in a new light, and can make
> them better programmers overall.
>

As you mentioned beginners books for Haskell I couldn't resist
plugging Graham Huttons excellent beginners book "Programming in
Haskell":

http://www.cs.nott.ac.uk/~gmh/book.html

It is based on 10 years of teaching a first year undergraduate course
and is certainly accessible I believe. I've taught an undergraduate
course myself using it.

There is also the this book which complements Graham's quite well:

http://www.realworldhaskell.org/blog/

I agree with David in that it is asking the wrong question as to
whether there is a model of a computer that fits with Haskell. Haskell
is based on a different model of computation. Conceptually, Haskell
programs are executed by rewriting expressions not by manipulating
memory in a machine.

A trivial example:

Here's a function to append a list onto a list:

append :: [a] -> [a] -> [a]
append [] ys = ys
append (x:xs) ys = x:append xs ys

and here we run it (on paper, no machine required :) ) on a some lists
by applying the above rules where the match:

Note: [1,2] is syntactic sugar for (1:(2:[]))

append [1,2] [3,4]
= { apply first pattern match equation }
1 : append [2] [3,4]
= { apply first pattern match equation }
1 : 2 : append [] [3,4]
= { apply second pattern match equation }
1 : 2 : [3,4]
= { just syntactic sugar }
[1,2,3,4]

I wouldn't be as bold as to suggest that Haskell should replace C but
certainly it is a nice language to use in my opinion. Does it explain
how a computer works? No. Does it explain 'computation'? Yes.






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