Loosely typed languages may offer certain advantages in terms of ease of use and flexibility, but they bring another challenge: its difficult to know what it is youre looking at. With no compiler type checking, its hard to compare two things, and that becomes extremely problematic when youre working with languages like, say, JavaScript.

Ruby, in its quest to make programmers happy, took a simplistic approach to the Truthy vs. Falsy problem. False is false. Nil is false. Everything else is True. Ruby is often used by web developers, who may be more comfortable in languages like JavaScript and PHP.

That is presumably why Lisa found this debacle in her code base, placed there by a co-worker who preferred other web languages:

  def equivalent_values(old_value, new_value)
    if (old_value == false && new_value == "0") ||
       (old_value == "0" && new_value == false) ||
       (old_value == "1" && new_value == true) ||
       (old_value == true && new_value == "1")
      return true
    end
    if (old_value.is_a?(Array) && old_value[0].to_s == new_value.to_s && old_value.size == 1) ||
       (new_value.is_a?(Array) && new_value[0].to_s == old_value.to_s && new_value.size == 1)
      return true
    end
    false
  end

Yes, this also does some type coercion, after a fashion, so its a little broader that mere Truthiness, so my initial description may have been incomplete or misleading. For this block of code, that wouldnt be the first time. For reasons no one can explain, this method was part of a module called TimestampHelper.

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http://thedailywtf.com/articles/the-coercive-types