Is Haskell a Type System?

I find that having worked in Haskell for two years, I could internalize a whole bunch of the type discipline into my own being. Even though there's no checks, right, I know when I'm writing a function that I want to return a string,. And then I also know closure programmers who will say, oh, I'll return a string or nil and you're going to need an if statement somewhere else where the return value gets read. It's really much more useful to compare specific type systems. Right? So like it doesn't, it's like calling it a type error. But maybe I would have chosen to switch, but probably not.