feat: struct schematics (#15)

Author: mhanberg

README.md

@@ -28,6 +28,8 @@ There are 12 builtin schematics that you can use to build new schematics that fi
 
 Literals can be used as schematics and are unified with `==` semantics.
 
+Struct literals can be used as schematics, and the input is unified by seeing if it is an instance of the given struct.
+
 ## Example
 
 Let's take a look at an example schematic for a JSON-RPC request for a bookstore API.

lib/schematic/unification.ex

@@ -16,7 +16,17 @@ defimpl Schematic.Unification, for: Schematic do
 end
 
 defimpl Schematic.Unification, for: Any do
-  def unify(literal, value, _ \\ nil) do
+  def unify(schematic, input, _ \\ nil)
+
+  def unify(%schematic_mod{}, %input_mod{} = input, _) do
+    if schematic_mod == input_mod do
+      {:ok, input}
+    else
+      {:error, "expected %#{schematic_mod}{}"}
+    end
+  end
+
+  def unify(literal, value, _) do
     if literal == value do
       {:ok, value}
     else

test/schematic_test.exs

@@ -348,6 +348,12 @@ defmodule SchematicTest do
       assert {:error, "expected false"} = unify(schematic, true)
     end
 
+    test "struct literal" do
+      schematic = %HTTPRequest{}
+
+      assert {:ok, %HTTPRequest{body: "hi"}} = unify(schematic, %HTTPRequest{body: "hi"})
+    end
+
     test "raw/2" do
       schematic = raw(fn n, _ -> n > 10 end, message: "must be greater than 10")