Merge pull request #30 from versecafe/fix-cartesian-product-types

Allow cartesian product of (a, b) instead of only (a, a)

src/gleam_community/maths/combinatorics.gleam

@@ -652,10 +652,10 @@ fn do_list_permutation_with_repetitions(
 ///     </a>
 /// </div>
 ///
-pub fn cartesian_product(xset: set.Set(a), yset: set.Set(a)) -> set.Set(#(a, a)) {
+pub fn cartesian_product(xset: set.Set(a), yset: set.Set(b)) -> set.Set(#(a, b)) {
   xset
-  |> set.fold(set.new(), fn(accumulator0: set.Set(#(a, a)), member0: a) {
-    set.fold(yset, accumulator0, fn(accumulator1: set.Set(#(a, a)), member1: a) {
+  |> set.fold(set.new(), fn(accumulator0: set.Set(#(a, b)), member0: a) {
+    set.fold(yset, accumulator0, fn(accumulator1: set.Set(#(a, b)), member1: b) {
       set.insert(accumulator1, #(member0, member1))
     })
   })

test/gleam_community/maths/combinatorics_test.gleam

@@ -72,7 +72,7 @@ pub fn int_combination_test() {
 
   combinatorics.combination(7, 5, option.Some(combinatorics.WithRepetitions))
   |> should.equal(Ok(462))
-  // NOTE: Tests with the 'combination' function that produce values that exceed 
+  // NOTE: Tests with the 'combination' function that produce values that exceed
   // precision of the JavaScript 'Number' primitive will result in errors
 }
 
@@ -697,4 +697,11 @@ pub fn example_test() {
   |> should.equal(
     set.from_list([#(1.0, 1.0), #(1.0, 2.0), #(10.0, 1.0), #(10.0, 2.0)]),
   )
+
+  // Cartesian product of two sets with different types
+  set.from_list(["1", "10"])
+  |> combinatorics.cartesian_product(set.from_list([1.0, 2.0]))
+  |> should.equal(
+    set.from_list([#("1", 1.0), #("1", 2.0), #("10", 1.0), #("10", 2.0)]),
+  )
 }