In vetr: Trust, but Verify

The following packages also perform related tasks, although we do not review them:

valaddin v0.1.0 by Eugene Ha, a framework for augmenting existing functions with validation contracts. Currently the package is undergoing a major overhaul so we will add it to the comparison once the new release (v0.3.0) is out.
ensurer v1.1 by Stefan M. Bache, a framework for flexibly creating and combining validation contracts. The development version adds an experimental method for creating type safe functions, but it is not published to CRAN so we do not test it here.
validate by Mark van der Loo and Edwin de Jonge, with a primary focus on validating data in data frames and similar data structures.
assertr by Tony Fischetti, also focused on data validation in data frames and similar structures.
types by Jim Hester, which implements but does not enforce type hinting.
argufy by Gábor Csárdi, which implements parameter validation via roxygen tags (not released to CRAN).
typed by Antoine Fabri, which enforces types of symbols, function parameters, and return values.