start at some basic passes

pass/pass.go

@@ -0,0 +1,17 @@
+package pass
+
+import "github.com/mmcloughlin/avo"
+
+// TODO(mbm): pass types
+
+// FunctionPass builds a full pass that operates on all functions independently.
+func FunctionPass(p func(*avo.Function) error) func(*avo.File) error {
+	return func(f *avo.File) error {
+		for _, fn := range f.Functions {
+			if err := p(fn); err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+}