For sure. Then you get a compiler error.
Programming Haskell without understand the type system and lambda calculus is not possible.
Edit: thanks for downvoting me. If you believe that you can program Haskell without understanding the basics of Functional Programming and without understanding the type system, then you live in an alternate reality or want to evangelize Haskell.
λx. x (λf y.y f (f 1) ) (λx1 f x.f (x1 f x))
λx y f x.(x f) (y f x)
Even the type system - you need to understand some tiny amount - you can only add ints to ints etc. The more complicated stuff, the type inference, the monads etc - can be ignored until later.
Haskell can be used without understanding - almost all programming languages can. That's why we have so many newbie bugs.
Let's look at a few chapter titles of Real World Haskell.
Chapter 2: Types and Functions
Chapter 3: Defining types, streamlining functions
Chapter 4: Functional Programming
Chapter 6: Using Typeclasses
Chapter 14: Monads
Chapter 15: Programming with Monads
Chapter 18: Monad transformers
I think the biggest issue is with those developers that never got a degree or were unfortunate to land in a degree that taught programming languages instead of programming concepts.