Add lots of utilties, initial builtins

src/utility.c

@@ -0,0 +1,113 @@
+#include "nihilispm.h"
+#include "nihilispm_internal.h"
+#include "nihilispm_utility.h"
+
+#include <stddef.h>
+#include <stdbool.h>
+#include <string.h>
+
+struct nl_object *nl_car(struct nl_object *list) {
+    if (list == NULL || list->type != NL_TYPE_CELL) {
+        return NULL; // TODO: Return an error type
+    }
+
+    struct nl_object *car = list->cell.car;
+    if (car == NULL) {
+        return nl_nil_create();
+    }
+
+    return car;
+}
+
+struct nl_object *nl_cdr(struct nl_object *list) {
+    if (list == NULL || list->type != NL_TYPE_CELL) {
+        return NULL; // TODO: Return an error type
+    }
+
+    struct nl_object *cdr = list->cell.cdr;
+    if (cdr == NULL) {
+        return nl_nil_create();
+    }
+
+    return cdr;
+}
+
+struct nl_object *nl_nil_create() {
+    return nl_cell_create(NULL, NULL);
+}
+
+struct nl_object *nl_t_create() {
+    return nl_symbol_create(strdup("t"));
+}
+
+struct nl_object *nl_predicate(bool value) {
+    if (value) {
+        return nl_t_create();
+    } else {
+        return nl_nil_create();
+    }
+}
+
+struct nl_object *nl_list_length(struct nl_object *list) {
+    if (list == NULL || list->type != NL_TYPE_CELL) {
+        return NULL; // TODO: Return an error type
+    }
+
+    struct nl_object *node = list;
+    if (list->cell.car == NULL) {
+        return nl_int_create(0);
+    }
+
+    int length = 1;
+    while (node->cell.cdr != NULL) {
+        node = node->cell.cdr;
+        length++;
+    }
+
+    return nl_int_create(length);
+}
+
+struct nl_object *nl_list_nth(struct nl_object *list, int n) {
+    if (list == NULL || list->type != NL_TYPE_CELL) {
+        return NULL; // TODO: Return an error type
+    }
+
+    int length = nl_list_length(list)->integer;
+    if (length <= n) {
+        return NULL; // TODO: Return an error type
+    }
+
+    struct nl_object *node = list;
+    for (int i = 0; i < n; i++) {
+        node = node->cell.cdr;
+    }
+
+    return node->cell.car;
+}
+
+struct nl_object *nl_truthy(struct nl_object *obj) {
+    // TODO: Implement me
+    return NULL;
+}
+
+struct nl_object *nl_tuple_create(struct nl_object *obj0, struct nl_object *obj1) {
+    struct nl_object *tuple = nl_cell_create(obj0, NULL);
+    nl_list_append(tuple, obj1);
+    return tuple;
+}
+
+struct nl_object *nl_list_append(struct nl_object *list, struct nl_object *obj) {
+    struct nl_object *iter = list;
+
+    if (list->cell.car == NULL) {
+        list->cell.car = obj;
+        return list;
+    }
+
+    while (iter->cell.cdr != NULL) {
+        iter = iter->cell.cdr;
+    }
+    iter->cell.cdr = nl_cell_create(obj, NULL);
+
+    return list;
+}