Why is it worth spending time on type theory? (2013)
$\begingroup$ Type theory is to set theory what computable functions are to usual functions. It's a constructive setting for doing mathematics, so it allows to deal carefully with what can or can't be computed/decided (see intensionality vs. extensionality, or the different notions of reduction and conversion in $\lambda$-calculus). Furthermore, just like category theory, it gives a great insight on how certain mathematical objects are nothing but particular cases of a general construction, in