Why are (constant) expressions not evaluated at compile time in Haskell?

Question

I am currently learning Haskell, and there is one thing that baffles me:

When I build a complex expression (whose computation will take some time) and this expressio

Answer 1

You may like this reddit thread. The compiler could try to do this, but it could be dangerous, as constants of any type can do funny things like loop. There are at least two solutions: one is supercompilation, not available as part of any compiler yet but you can try prototypes from various researchers; the more practical one is to use Template Haskell, which is GHC's mechanism for letting the programmer ask for some code to be run at compile time.