C言語でコンスセルとその他諸々

cons_cell.c

#include<stdio.h>
#include<stdlib.h>

typedef struct cell {
  int car;
  struct cell *cdr;
} _cell;

struct cell *cons(int car, struct cell *cdr) {
  struct cell *new;

  new = malloc(sizeof(_cell));

  new->car = car;
  new->cdr = cdr;

  return new;
};

struct cell *range(int start, int end) {

  int tmp = end-1;
  struct cell *res;

  res = cons(tmp, NULL);

  while(start!=tmp) {
    tmp--;
    res = cons(tmp, res);
  }

  return res;
  
};

void pprint(struct cell *coll) {
  if(coll != NULL) {
    printf("(%d ", coll->car);
    pprint(coll->cdr);
    printf(")");
  } else {
    printf("nil");
    return 0;
  }
}

int main(void) {
  
  printf("range(1,40) => ");
  pprint(range(1,40));
  printf("\ncons(1, cons(2, NULL)) => ");
  pprint(cons(1, cons(2, NULL)));
  printf("\n");

  return 0;
};