Type checker does not enforce that generic parameters are generic

[edwardpeters]

Describe the bug
If you declare a function as generic, but implement it in a way that only works for a single type, no error is given

To Reproduce
Compile the following code snippet:

typeErrorTest : t -> t
typeErrorTest x = if x then True else False

This does not throw an error with make or make -f.

Expected behavior
I would expect this code to throw an error, as you declared the function to use a generic type t, which cannot be inferred to be a specific type. (This is the behavior using Elm).

Desktop (please complete the following information):

• OS: OSX
• Browser: Unused
• Version: 2.89.0