/* Unit Test: Case Expressions */
/* Tests: Pattern matching, wildcards, nested cases */

/* Basic case expressions */
factorial : n -> 
  when n is
    0 then 1
    _ then n * (@factorial (n - 1));

grade : score -> 
  when score is
    score >= 90 then "A"
    score >= 80 then "B"
    score >= 70 then "C"
    _  then "F";

/* Test case expressions */
fact5 : factorial 5;
grade1 : grade 95;
grade2 : grade 85;
grade3 : grade 65;

/* Test results */
..assert fact5 = 120;
..assert grade1 = "A";  /* 95 >= 90, so matches first case */
..assert grade2 = "B";  /* 85 >= 80, so matches second case */
..assert grade3 = "F";  /* 65 < 70, so falls through to wildcard */

/* Multi-parameter case expressions */
compare : x y -> 
  when x y is
    0 0 then "both zero"
    0 _ then "x is zero"
    _ 0 then "y is zero"
    _ _ then "neither zero";

test1 : compare 0 0;
test2 : compare 0 5;
test3 : compare 5 0;
test4 : compare 5 5;

..assert test1 = "both zero";
..assert test2 = "x is zero";
..assert test3 = "y is zero";
..assert test4 = "neither zero";

..out "Case expressions test completed";