Re: What is a functional language? (Was: Re: Functional languages and ... (was: Cryptarithm solver ...))
On Wed, Sep 22, 1999 at 04:57:58PM +0100, D. Tweed wrote: > Firstly let me check that we mean the same thing by _higher order > functions, namely they are functions which return functions ... or take functions as parameters. Such as map, foldr, iterate, etc. -- %%% Antti-Juhani Kaijanaho % [EMAIL PROTECTED] % http://www.iki.fi/gaia/ %%% "" (John Cage)
What is a functional language? (Was: Re: Functional languages and ... (was: Cryptarithm solver ...))
On Wed, Sep 22, 1999 at 02:53:03PM +0100, Claus Reinke wrote: > Functional programming, i.e., programming with functions, is possible in > languages that do not support all features that have become common in > many functional languages. [eg. higher-order functions] Well then, it appears that I have a mistaken idea of what functional programming is. Can you give me, to cure my ignorance, a few examples of languages (preferably ones that are in use nowadays) that are *not* functional and the reasons why this is so. Is C functional, since it is possible to program with functions in it? > From the perspective of numerical programmers, you could also ask: Isn't > compilation of high-level array operations into efficient code a > necessary part of every useful (FP) language? I would definitely agree with that question if you didn't refer to FP in it. You don't define FP as "useful", do you? -- %%% Antti-Juhani Kaijanaho % [EMAIL PROTECTED] % http://www.iki.fi/gaia/ %%% "" (John Cage)
Re: What is a functional language? (Was: Re: Functional languages and ... (was: Cryptarithm solver ...))
On Wed, 22 Sep 1999, Antti-Juhani Kaijanaho wrote: > On Wed, Sep 22, 1999 at 02:53:03PM +0100, Claus Reinke wrote: > > Functional programming, i.e., programming with functions, is possible in > > languages that do not support all features that have become common in > > many functional languages. > [eg. higher-order functions] > > Well then, it appears that I have a mistaken idea of what functional > programming is. Can you give me, to cure my ignorance, a few examples > of languages (preferably ones that are in use nowadays) that are *not* > functional and the reasons why this is so. Is C functional, since it > is possible to program with functions in it? Firstly let me check that we mean the same thing by _higher order functions, namely they are functions which return functions. This is different from the idea that functions are _pure_, namely that the value returned by a function depends _only_ on its arguments (and not on some state, as represented by either local `static' variables or global varables in C). To my understanding, most people would call a language functional if the natural way of using it leads to a very large percentage of the computation being done with pure functions, and it's not if it's natural to use a significant percentage of comptation which involves state, either locally or globally. (Note that repeated assignment is clearly stateful, so any language where this is a natural way of doing things is not functional) So there's no sharp dividing line :-S Haskell is functional, although it has facilities for dealing with state via monads. ML is also functional language, even though it has references which allow it to deal with state. Emacs-Lisp is not really a functional language because so much of it involves manipulating state; however it incorporates some of the ideas from functional programming as it existed in the late seventies. C is not functional because the most natural way of coding many algorithms involves using subroutines (misleadingly named functions!) with either internal state (even if this is only assignment within loops!) or global state. Neither are Pascal, Modula-x, Oberon, perl,... This is despite the fact that you could write C/... programs that made sure that the subroutines were all functions and that you only ever used single assignment because it's not natural to do it that way. (In some ways it's like asking `what characterises an alcoholic?': you need to note that some people who aren't occasionally drink to excess and that alcoholics can go without a drink for short periods.) ___cheers,_dave__ email: [EMAIL PROTECTED] "He'd stay up all night inventing an www.cs.bris.ac.uk/~tweed/pi.htm alarm clock to ensure he woke early work tel: (0117) 954-5253 the next morning"-- Terry Pratchett
Re: What is a functional language? (Was: Re: Functional languages and ... (was: Cryptarithm solver ...)) (fwd)
On Wed, 22 Sep 1999, Antti-Juhani Kaijanaho wrote: > On Wed, Sep 22, 1999 at 02:53:03PM +0100, Claus Reinke wrote: > > Functional programming, i.e., programming with functions, is possible in > > languages that do not support all features that have become common in > > many functional languages. > [eg. higher-order functions] > > Well then, it appears that I have a mistaken idea of what functional > programming is. Can you give me, to cure my ignorance, a few examples > of languages (preferably ones that are in use nowadays) that are *not* > functional and the reasons why this is so. Is C functional, since it > is possible to program with functions in it? > <* MUNCHED A LOT HERE *> Actually, it is my understanding that C can be used as a functional language. There is even a book out there called "Functional C" that some day I really want to take a look at. I am not really sure what it is about :) Of course, you have to use a lot of discipline I suppose! SOrt of like doing oop in Python or Perl requires a lot of discipline :) CHeers!
