Discussion on: Towards More Effective Software Testing: Equivalence Partitioning and Domain Analysis

[Alex Weisberger]

That does show the power of pattern matching. You can capture a lot of permutations in a relatively small amount of code this way.

I'm partial to having descriptive names for operations, so I like how the current isLegalMove reads like English: areCardsDifferentColor && areRanksInDescendingOrder reads exactly like the game rules are stated.

That can remain the same and we can use this technique to reimplement areCardsDifferentColor:

let areCardsDifferentColor = (c1, c2) => 
  switch (c1.suit, c2.suit) {
  | (Clubs | Spades, Hearts | Diamonds) => true
  | (Hearts | Diamonds, Clubs | Spades) => true
  | _ => false
  };

It's definitely fun to think about the best way to express things.

[Yawar Amin]

Yeah, the way you broke down the implementation into helper functions at a lower level of abstraction–the step method–is probably more maintainable overall!