2 files changed, 43 insertions, 12 deletions

diff --git a/MLKRoot.m b/MLKRoot.m
index e3dca4f..4ba7ac7 100644
--- a/MLKRoot.m
+++ b/MLKRoot.m
@@ -26,6 +26,7 @@
 #import "MLKInteger.h"
 #import "MLKSingleFloat.h"
 #import "MLKDoubleFloat.h"
+#import "NSObject-MLKPrinting.h"
 #import "runtime-compatibility.h"
 #import "util.h"
 
@@ -48,19 +49,8 @@ static id truify (BOOL value)
   return (value ? (id) [cl intern:@"T"] : nil);
 }
 
-static id stringify (id thing)
-{
-  // FIXME.
-  if (!thing)
-    return @"NIL";
-  if ([thing isKindOfClass:[NSString class]])
-    return thing;
-  else if ([thing isKindOfClass:[MLKSymbol class]])
-    return [thing name];
-}
-
 #define RETURN_VALUE(thing)                     \
-  return [NSArray arrayWithObject:nullify(thing)];
+  { return [NSArray arrayWithObject:nullify(thing)]; }
 
 
 @implementation MLKRoot
@@ -311,4 +301,27 @@ static id stringify (id thing)
 
   RETURN_VALUE ([cl intern:@"T"]);
 }
+
++(NSArray *) find_package:(NSArray *)args
+{
+  NSString *name = stringify (denullify ([args objectAtIndex:0]));
+  MLKPackage *package = [MLKPackage findPackage:name];
+
+  if (package)
+    {
+      RETURN_VALUE (package);
+    }
+  else
+    {
+      [NSException raise:@"MLKNoSuchPackageError"
+                   format:@"The package %@ does not exist",
+                          [name descriptionForLisp]];
+      return nil;
+    }
+}
+
++(NSArray *) string:(NSArray *)args
+{
+  RETURN_VALUE (stringify (denullify ([args objectAtIndex:0])));
+}
 @end
diff --git a/util.h b/util.h
index 71dc3d6..0e27fc0 100644
--- a/util.h
+++ b/util.h
@@ -1,4 +1,5 @@
 #include "runtime-compatibility.h"
+#include <Foundation/NSException.h>
 #include <Foundation/NSNull.h>
 
 #define DEFINE_GMP_OPERATION(SIGNATURE, TYPE, GMPOP, OBJTYPE, CONSTRUCTOR) \
@@ -18,6 +19,7 @@
 
 static id nullify (id value) __attribute__ ((pure, unused));
 static id denullify (id value) __attribute__ ((pure, unused));
+static id stringify (id value) __attribute__ ((pure, unused));
 
 static id nullify (id value)
 {
@@ -34,3 +36,19 @@ static id denullify (id value)
   else
     return value;
 }
+
+static id stringify (id thing)
+{
+  // FIXME: Some cases may be missing.
+  if (!thing)
+    return @"NIL";
+  if ([thing isKindOfClass:[NSString class]])
+    return thing;
+  else if ([thing isKindOfClass:[MLKSymbol class]])
+    return [thing name];
+
+  [NSException raise:@"MLKTypeError" format:@"Can't coerce %@ to a string.",
+                                            [thing descriptionForLisp]];
+
+  return nil;
+}