/prog/ - COND — World4ch

Name: Anonymous 2012-09-05 10:08

Why doesn't C have the sugar syntax for COND yet?

Name: Anonymous 2012-09-05 10:43

Because it has macros.

Name: Anonymous 2012-09-05 10:47

It doesn't need it. case statements are C's equivalent for executing code, and nested x ? y : z works well for inline values.

Name: Anonymous 2012-09-05 12:02

>>3
case statements are in no manner equivalent to cond, neither are ?: statements due to their rules.

The only thing that can do the same as cond would be a chain of if/elses

Name: Anonymous 2012-09-05 13:09

Op hasn't discovered c++ template metaprogramming. It is more powerful than lisp macros (gay)

Name: Anonymous 2012-09-05 13:59

>>5
LOL

Name: Anonymous 2012-09-05 14:33

>>4
I meant something like this:

(define (foo x)

  (cond ((= x 10) 5)

        ((= x 20) 6)

        (#t 0)))

Becoming this in C:

int foo(int x) {

    switch (x) {

        case 10: return 5;

        case 20: return 6;

        default: return 0;

    }

}

That doesn't work for conditions like (> x 0), but it fits some uses of cond well. When wouldn't ?: statements work?

Name: Anonymous 2012-09-05 15:21

Just use if/else chains you retarded LISPweenie

Name: Anonymous 2012-09-05 15:48

That's some dirty code, but it fucking works!

int cond(int count, ...)

{

  assert(count > 0);



  va_list ap;

  va_start(ap, count);



  int predicate = 0, result;

  while (count-- || !predicate)

  {

    predicate = va_arg(ap, int);

    result    = va_arg(ap, int);

  }



  va_end(ap);

  return result;

}



int y = cond(3,

             x < 10,  5,

             x == 10, 6,

             x > 10,  7);

Name: Anonymous 2012-09-05 15:53

>>9
Now let it take lambda functions as arguments to be performed when one of the conditions is found to be true

Name: Anonymous 2012-09-05 16:00

>>10
IHBT

Name: Anonymous 2012-09-05 16:34

print((x < 10 | -1 |: x = 10 | TRUE |: x > 10 | +1.0 | "unordered"))
Algol 68 has a true multi-branch conditional. Branches that yield different types yield a union of those types.

(  IF    CASE

|: THEF  INSE       # removed in the Revised Report #

|  THEN  IN

|: ELIF  OUSE

|  ELSE  OUT

)  FI    ESAC

Name: Anonymous 2012-09-05 18:02

C needs a progn

COND

1 Name: Anonymous 2012-09-05 10:08

2 Name: Anonymous 2012-09-05 10:43

3 Name: Anonymous 2012-09-05 10:47

4 Name: Anonymous 2012-09-05 12:02

5 Name: Anonymous 2012-09-05 13:09

6 Name: Anonymous 2012-09-05 13:59

7 Name: Anonymous 2012-09-05 14:33

8 Name: Anonymous 2012-09-05 15:21

9 Name: Anonymous 2012-09-05 15:48

10 Name: Anonymous 2012-09-05 15:53

11 Name: Anonymous 2012-09-05 16:00

12 Name: Anonymous 2012-09-05 16:34

13 Name: Anonymous 2012-09-05 18:02