On Mon, 8 Oct 2007, Alistair Bayley wrote:
On 08/10/2007, Henning Thielemann <[EMAIL PROTECTED]> wrote:
You cannot turn any programmer into a disciplined programmer just by
giving him a well designed language. I you try so, they will not like to
use that language, will leave that language as soon as possible or they
try to adapt the language to their style of programming.
Well, I wasn't suggesting you'll create great programmers overnight,
but you might expect that their appreciation of good design might
improve after some Haskell exposure. Also, Haskell simply doesn't
support some of the things that are common causes of errors in the
enterprisey-language world. I recall reading something about one of
the most common causes of errors in novice programs being type errors
(presumably, once they'd got the program to compile i.e. there were no
syntactic errors). And I'm under the (possibly mistaken) impression
that some of the common errors non-novice programmers make are
aliasing bugs, and/or use of global variables. Does anyone have
references to studies confirming (or refuting) this?
Thus, what happens today? People ask Haskell-Cafe how to implement global
variables and they are advised to use IORefs and unsafePerformIO, although
the better answer is: "Why do you want to do this?" Even "Tackling the
awkward squad" considers unsafePerformIO an acceptable tool for handling
global configuration files.
People who are used to weak typing will use a type like
data Number = Int Int | Float Float | ...
for numbers, or even String for everything, they will use numbers, where
enumerations are more appropriate and so on.
I think that the ease with which you can create a new type in Haskell
(and derive useful classes like Enum, Show, etc) makes it more likely
that a programmer will use an appropriate domain-specific type, rather
than just reuse String, Int, or Float.
I know of popular Haskell libraries which ignore disciplined type design,
but I do not want to hurt their authors ...
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