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When functional languages can be accepted by industry?
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Date: 2000-04-09 (23:31)
From: Jean-Christophe Filliatre <filliatr@c...>
Subject: Re: When functional languages can be accepted by industry?

In his message of Mon April 3, 2000, Dennis (Gang) Chen writes: 

> Are there other features of functional language which will attract industry?

- Garbage Collection. (how many memory  leaks in C++ programs? how many
  bugs related to  memory unsafely de-allocated?) And ocaml's  GC is a
  very good one.

- Strong Typing. (how many bugs  are related to unsafe type assumptions
  about pointers in other languages?)

  Above all, strong  typing allows you to develop  and experiment with
  your code very quickly. Let me explain that point.

  When  you add  a  constructor to  a  type, or  when  you change  the
  definition of  a type, or the type  of a function, you  just have to
  recompile and  the compiler will find  all the places  which are now
  ill-typed, or  where a pattern-matching is  non-exhaustive, etc. and
  this is possible because of strong-typing.

  In practice, it appears to be  one of the most important property of
  ocaml's compiler. I use it hundreds of times every day. Whatever the
  size and the complexity of your code are, the compiler will find the
  needed  changes. With  other languages,  you have  to think  hard to
  remember  the places  where changes  are  now needed,  and that's  a
  reason for code inertia (and for bugs, too).

- Recursive data-types.  I didn't follow your arguments  about C++ STL
  versus lists in functional  programming. Of course, lists are almost
  always bad  data-structures. But  a good functional  programmer does
  not use lists as data-structures  (a Lisp programmer, may be :-) but
  rather balanced trees,  Patricia trees, binomial heaps, hash-tables,
  etc. Moreover, most of  these datatypes are persistent, an essential
  property  is  several  applications  (whether  in-place  destructive
  datastructures  require explicit  copies, which  are time  and space
  consuming). You should read  Chris Okasaki's book "Purely Functional
  Data Structures".

Strong typing, recursive data-types and  a good GC are essential tools
for the programmer: you develop  quicker, your code is safer (does not
crash on a seg fault) and is  easier to maintain and to modify. Do you
still need other arguments?

Jean-Christophe Filliatre    
  Computer Science Laboratory   Phone (650) 859-5173
  SRI International             FAX   (650) 859-2844
  333 Ravenswood Ave.           email
  Menlo Park, CA 94025, USA     web