Add `mruby-eval` to `default.gembox`.
MODIFY
mrbgems/default.gembox
mrbgems/default.gembox
@@ -89,6 +89,9 @@ MRuby::GemBox.new do |conf|
# Use Method/UnboundMethod class
conf.gem :core => "mruby-method"
+ # Use eval()
+ conf.gem :core => "mruby-eval"
+
# Use mruby-compiler to build other mrbgems
conf.gem :core => "mruby-compiler"
end

Add `mruby-eval` to `default.gembox`.