array builtins

builtins/max.go

@@ -0,0 +1,29 @@
+package builtins
+
+import (
+	"monkey/object"
+	"sort"
+)
+
+// Max ...
+func Max(args ...object.Object) object.Object {
+	if len(args) != 1 {
+		return newError("wrong number of arguments. got=%d, want=1",
+			len(args))
+	}
+
+	if a, ok := args[0].(*object.Array); ok {
+		// TODO: Make this more generic
+		xs := make([]int, len(a.Elements))
+		for n, e := range a.Elements {
+			if i, ok := e.(*object.Integer); ok {
+				xs = append(xs, int(i.Value))
+			} else {
+				return newError("item #%d  not an `int` got=%s", n, e.Type())
+			}
+		}
+		sort.Ints(xs)
+		return &object.Integer{Value: int64(xs[len(xs)-1])}
+	}
+	return newError("argument #1 to `max` expected to be `array` got=%T", args[0].Type())
+}