gistfile1.c

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

typedef struct node {
	int value;
	struct node *next;
} node;

int increment(int);
int square(int);
node * map(node *l, int (*func)(int));
node * list_add(node *head, int value);

int 
main()
{
	node *l = NULL;
	l = list_add(l, 3);
	l = list_add(l, 4);
	l = list_add(l, 5);
	map(l, square);

	return 0;
}

node *
list_add(node *head, int value)
{
	if (head == NULL) {
		head = malloc(sizeof(node));
		head->value = value;
		head->next = NULL;		
	} else {
		node *n = head;
		while (n->next != NULL)
			n = n->next;
		n->next = malloc(sizeof(node));
		n->next->value = value;
		n->next->next = NULL;
	}
	return head;
}

node *
map(node *head, int (*func)(int))
{	
	node *i = NULL;

	for(node *n=head; n != NULL; n=n->next) 
	{
		while(i != NULL)
		{
			list_add(i, func(n->value));

		}
	}

	return i;
}

int 
square(int n)
{
	return n * n;
}

int 
increment(int n)
{
	return n + 1;
}