Parse, Don't Validate – In a Language That Doesn't Want You To

The article discusses how TypeScript developers often "validate" data (checking if it's correct) rather than "parsing" it (transforming it into a more precise type that the compiler remembers). Unlike languages like Haskell or Elm that encourage parsing through their type systems, TypeScript's structural typing allows validation to be forgotten immediately after it occurs, leading to repeated checks throughout code. The author demonstrates using branded types as a workaround to create TypeScript types that preserve validation information and prevent invalid data from being passed to functions.