2 files changed, 55 insertions, 0 deletions
diff --git a/lua/mason-core/optional.lua b/lua/mason-core/optional.lua
index cc40da77..d5055c9c 100644
--- a/lua/mason-core/optional.lua
+++ b/lua/mason-core/optional.lua
@@ -62,6 +62,16 @@ function Optional:or_else_get(supplier)
     end
 end
 
+---@param supplier fun(value: any): Optional
+---@return Optional
+function Optional:and_then(supplier)
+    if self:is_present() then
+        return supplier(self._value)
+    else
+        return self
+    end
+end
+
 ---@param supplier fun(): Optional
 ---@return Optional
 function Optional:or_(supplier)
diff --git a/tests/mason-core/optional_spec.lua b/tests/mason-core/optional_spec.lua
index b1a4f41a..fed6deba 100644
--- a/tests/mason-core/optional_spec.lua
+++ b/tests/mason-core/optional_spec.lua
@@ -92,3 +92,48 @@ describe("Optional.ok_or()", function()
         assert.equals("I'm empty.", result:err_or_nil())
     end)
 end)
+
+describe("Optional.or_()", function()
+    it("should run supplier if value is not present", function()
+        local spy = spy.new(function()
+            return Optional.of "Hello world!"
+        end)
+        assert.same(Optional.of "Hello world!", Optional.empty():or_(spy))
+        assert.spy(spy).was_called(1)
+
+        assert.same(Optional.empty(), Optional.empty():or_(Optional.empty))
+    end)
+
+    it("should not run supplier if value is present", function()
+        local spy = spy.new(function()
+            return Optional.of "Hello world!"
+        end)
+        assert.same(Optional.of "Hello world!", Optional.of("Hello world!"):or_(spy))
+        assert.spy(spy).was_called(0)
+    end)
+end)
+
+describe("Optional.and_then()", function()
+    it("should run supplier if value is present", function()
+        local spy = spy.new(function(value)
+            return Optional.of(("%s world!"):format(value))
+        end)
+        assert.same(Optional.of "Hello world!", Optional.of("Hello"):and_then(spy))
+        assert.spy(spy).was_called(1)
+
+        assert.same(
+            Optional.empty(),
+            Optional.empty():and_then(function()
+                return Optional.of "Nothing."
+            end)
+        )
+    end)
+
+    it("should not run supplier if value is not present", function()
+        local spy = spy.new(function()
+            return Optional.of "Hello world!"
+        end)
+        assert.same(Optional.empty(), Optional.empty():and_then(spy))
+        assert.spy(spy).was_called(0)
+    end)
+end)