add compatibility checks

app/models/logic.rb

@@ -12,6 +12,15 @@ module Logic
       .find { |c| c.name == name }
   end
 
+  def self.compatible_type?(left, right)
+    case [left.type, right.type]
+    in [a, ^a] # syntax for same type
+      true
+    else
+      false
+    end
+  end
+
   def ds_eq(left, right) = Logic::Eq.new(left, right)
 
   def greater_than(left, right) = Logic::GreaterThan.new(left, right)

spec/models/logic_spec.rb

@@ -9,4 +9,9 @@ describe Logic do
 
     expect(Logic.from_h(greater_than(constant(1), constant(2)).to_h)).to eq(greater_than(constant(1), constant(2)))
   end
+
+  describe '.compatible_type?' do
+    it { expect(Logic.compatible_type?(constant(true), constant(true))).to be true }
+    it { expect(Logic.compatible_type?(constant(1), constant(true))).to be false }
+  end
 end