A Lamdera package. It is not on package.elm-lang.org: the Lamdera compiler provides it, from static.lamdera.com, so lamdera install works and elm install does not.
Lamdera.Wire3 contains all the built-in codecs used by Lamdera
It is the third version for generalised usage.
floor is one of few functions that turn integer floats in js into typed integers in Elm, e.g. the Float 3 into the Int 3.