compactness in writing and also namespace pollution .. ;^) Vasili On Fri, May 30, 2008 at 2:12 AM, Jonathan Cast <jonathanccast@fastmail.fm> wrote:

On 29 May 2008, at 11:46 PM, Galchin, Vasili wrote:

Hello,

...

I don't want to write kludgy Haskell code!

typedef struct blah { int val1;

union {

int val2;

struct {

int val3;

int val4; } } } C_type;

question: in Haskell, can I embed definition of the "union" inside of the C typedef, i.e. recursion definition? Or must I have a separate definition for the "union" which I "instantiate" inside the Haskell "typedef", i.e. Haskell "data"?

Assuming all of these are semantic, you can say

newtype HS_type = HS_type (Int, Either Int (Int, Int))

But you lose named fields.

It's hard to give other advice without some idea of /why/ you want to do something like this.

jcc

my knowledge of point-free is from category theory. in what sense is Haskell point-free handle namespace pollution? Kind regards, Vasili On Fri, May 30, 2008 at 3:23 AM, Jonathan Cast <jonathanccast@fastmail.fm> wrote:

On 30 May 2008, at 12:29 AM, Galchin, Vasili wrote:

compactness in writing and also namespace pollution .. ;^)

...

I know what the advantages of C's notation are. But getting the best notation out of Haskell generally doesn't happen by trying to make your code look like C.

So the general answer to questions of the form `C can do x; can Haskell' is `No'. Don't do it like in C. It won't be idiomatic, it won't be elegant, and neither of us will like the results. Understand the features of Haskell that make your program compact, point-free (how Haskell handles namespace pollution), and elegant and use those. This will require a different factoring of your program vs. C. Sorry, but that's life.

jcc