"no variable or argument declarations are necessary."

Paul Rubin http
Fri Oct 7 13:53:17 CEST 2005


"Fredrik Lundh" <fredrik at pythonware.com> writes:
> use assert as the soonest possible point.  implementing "type gates" is
> trivial, if you think you need them.

What this is about (to me at least) is the edit-debug cycle.  Let's
say I write some Python code, using assert to validate datatypes.
Maybe I've made 4 errors.  I then write a test function and run it.
Boom, the first assert fails.  I fix the first error, run again.
Boom, the next assert fails.  Fix the next error, run again, boom,
fix, etc.  Four edit-debug cycles.

With static typing, I run the compiler, get 4 error messages, fix all
4, and can get on with the next phase of testing with three fewer edit
cycles.  That's a definite benefit of languages like Java.  It's not
imaginary.  Unit tests on Python code don't make it go away.  I have
less Java experience than Python experience by now, but I still find
that Java programs take me fewer iterations to get working than Python
programs.  The trouble is that Java has a thousand deficiencies that
outweigh that particular benefit, so overall I like Python a lot
better anyway.

Now some of the Python-is-perfect crowd seems to suffer from a "Blub
paradox" (http://c2.com/cgi/wiki?BlubParadox).  They see annoying,
static typed languages like C and Java, and they see pleasant,
dynamically typed languages like Python, and conclude that static
types = annoying, when in fact they can be orthogonal.  So, can there
be a language that's both statically typed, and pleasant?  I haven't
used one yet, but lately I've been reading about Haskell and want to
give it a try.  I keep finding statements like:

    To me, Haskell is what Python should have evolved to. As a long-time
    Python programmer, I have been very, very pleased with Haskell and am
    currently working on porting my code to it (and write new code in
    Haskell at every opportunity).
       (http://supybot.com/Members/jemfinch/haskell-sucks/document_view)

or:

    Using Haskell to develop OpenAFP.hs led to programs that eat constant
    2MB memory, scale linearly, and are generally 2OOM faster than my Perl
    library.

    Oh, and the code size is 1/10.
       (http://www.perl.com/pub/a/2005/03/03/pugs_interview.html -
        Autrijus also raves about how great the book "Types and
        Programming Languages" supposedly is--I'm trying to borrow
        a copy.  Yeah, this is a Perl comparison, but I think of
        Perl as being roughly equivalent to Python except a lot uglier).

or:

    Haskell is the least-broken programming language available today. C,
    C++, Perl, Python, Java, and all the other languages you've heard of
    are all much more broken, so debating their merits is pointless. :-)
    Unfortunately Real Life involves dealing with brokenness.
       (http://www106.pair.com/rhp/books.html)

or:
    
    In conducting the independent design review at Intermetrics, there
    was a significant sense of disbelief.  We quote from [CHJ93]: "It
    is significant that Mr. Domanski, Mr. Banowetz and Dr. Brosgol
    were all surprised and suspicious when we told them that Haskell
    prototype P1 (see appendix B) is a complete tested executable
    program.  We provided them with a copy of P1 without explaining
    that it was a program, and based on preconceptions from their past
    experience, they had studied P1 under the assumption that it was a
    mixture of requirements specification and top level design.  They
    were convinced it was incomplete because it did not address issues
    such as data structure design and execution order."
       (http://haskell.org/papers/NSWC/jfp.ps - this was from a bake-off
       for a military application where the Haskell solution had 85 lines
       of code to Ada's 767, C++'s 1105, and Relational Lisp's 274). 

Obviously I'm in the usual rose-colored-glasses phase of finding out
about something new and interesting, but I can't help thinking these
guys are onto something.  Quite a few of the Haskell Cafe mailing list
members seem to have come to Haskell from Python.  (Haskell tutorial:
http://www.isi.edu/~hdaume/htut/ - I've read most of this and it looks
pretty cool--definitely a steeper learning curve than Python but the
result looks a lot more powerful).



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