Work In Progress: an Empirical Study of Static Typing in Ruby

In this paper, we present an empirical pilot study of four skilled programmers as they develop programs in Ruby, a popular, dynamically typed, object-oriented scripting language. Our study compares programmer behavior under the standard Ruby interpreter versus using Diamondback Ruby (DRuby), which adds static type inference to Ruby. The aim of our study is to understand whether DRuby’s static typing is beneficial to programmers. We found that DRuby’s warnings rarely provided information about potential errors not already evident from Ruby’s own error messages or from presumed prior knowledge. We hypothesize that programmers have ways of reasoning about types that compensate for the lack of static type information, possibly limiting DRuby’s usefulness when used on small programs.