Galchin, Vasili wrote:
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"?
No. Each definition of a data type must occur at the top-level. Also, Haskell has only a very weak record system, a deficit that is generally agreed to be one of Haskell's greatest weaknesses. Like jcc, I'd also be interested what concrete problem prompted your question. While I have often found it annoying that in Haskell e.g. record labels are global in scope, I have never encountered a situation where I wanted to have lexically nested data type declarations. Cheers Ben