In one case the numbers get floated out and in the others they stay in the alternative.

This results in one being compiled as a CAF while the other gets recreated on the heap.

{-# LANGUAGE MagicHash, BangPatterns, ScopedTypeVariables #-}

import GHC.Prim
import GHC.Exts

func :: Int# -> Int# -> Int
func 1# 1# = 10
func 1# 2# = 20

foo :: Int# -> Int# -> Int
foo 1# 1# = 30
foo 2# 1# = 40