Why are people worried about types?

Every week in The REPL I have a section called: “People are worried about Types”. This is based on a section that Matt Levine (my favourite columnist) includes in his daily column “People are worried about bond market liquidity”, and the related “People are worried about unicorns”, and “People are worried about stock buybacks”.

The title is a joke (as is his), I don’t really think there are people worried about types, but it is interesting to see a small but steady flow of type or type related (schema, spec, e.t.c.) articles relating to Clojure each week.