1 files changed, 30 insertions, 0 deletions
diff --git a/aoc-2020-gleam/src/util/pos3.gleam b/aoc-2020-gleam/src/util/pos3.gleam
new file mode 100644
index 0000000..5525607
--- /dev/null
+++ b/aoc-2020-gleam/src/util/pos3.gleam
@@ -0,0 +1,30 @@
+import gleam/list
+import gleam/bool
+import gleam/set.{Set}
+
+pub type Pos3 =
+  #(Int, Int, Int)
+
+pub const zero = #(0, 0, 0)
+
+fn directions26() -> Set(Pos3) {
+  set.from_list({
+    use x <- list.flat_map(over: [-1, 0, 1])
+    use y <- list.flat_map(over: [-1, 0, 1])
+    use z <- list.flat_map(over: [-1, 0, 1])
+    let pos = #(x, y, z)
+    use <- bool.guard(when: pos == zero, return: [])
+    [pos]
+  })
+}
+
+pub fn add(p1: Pos3, p2: Pos3) -> Pos3 {
+  #(p1.0 + p2.0, p1.1 + p2.1, p1.2 + p2.2)
+}
+
+pub fn neighbours26(p: Pos3) -> Set(Pos3) {
+  directions26()
+  |> set.to_list
+  |> list.map(with: add(p, _))
+  |> set.from_list
+}