Type errors

src/base.c

@@ -3,6 +3,7 @@
 #include "hashtable.h"
 #include "lisp.h"
 
+#include <stdio.h>
 #include <string.h>
 
 const char *LISP_TYPE_NAMES[N_LISP_TYPES] = {
@@ -27,6 +28,18 @@ void *lisp_alloc_object(size_t size, LispValType type) {
     return obj;
 }
 
+void signal_type_error(LispVal *obj, size_t count,
+                       const LispValType types[count]) {
+    // TODO actually throw an error
+    fprintf(stderr, "Type error! Got: %s | Expected: (or ",
+            LISP_TYPE_NAMES[TYPE_OF(obj)]);
+    for (size_t i = 0; i < count; ++i) {
+        fprintf(stderr, "%s%s", LISP_TYPE_NAMES[i],
+                i < count - 1 ? " " : ")\n");
+    }
+    abort();
+}
+
 DEFINE_SYMBOL(nil, "nil");
 DEFINE_SYMBOL(t, "t");
 DEFINE_SYMBOL(unbound, "unbound");
@@ -71,7 +84,7 @@ DEFUN(make_symbol, "make-symbol", (LispVal * name), "(name)",
 }
 
 DEFUN(intern, "intern", (LispVal * name), "(name)", "") {
-    // TODO type checking
+    CHECK_TYPE(name, TYPE_STRING);
     LispVal *res = Fgethash(obarray, name, Qunbound);
     if (res != Qunbound) {
         return res;
@@ -80,3 +93,15 @@ DEFUN(intern, "intern", (LispVal * name), "(name)", "") {
     Fputhash(obarray, name, newsym);
     return newsym;
 }
+
+DEFUN(symbol_function, "symbol-function", (LispVal * sym, LispVal *resolve),
+      "(sym &optional resolve)", "") {
+    CHECK_TYPE(sym, TYPE_SYMBOL);
+    if (NILP(resolve)) {
+        return ((LispSymbol *) sym)->function;
+    }
+    while (!NILP(sym) && SYMBOLP(sym)) {
+        sym = ((LispSymbol *) sym)->function;
+    }
+    return sym;
+}