Tentatively start working on a language to analyze

Language.agda

@@ -0,0 +1,10 @@
+module Language where
+
+open import Data.String using (String)
+open import Data.Nat using (ℕ)
+
+data Expr : Set where
+    _+_ : Expr → Expr → Expr
+    _-_ : Expr → Expr → Expr
+    `_ : String → Expr
+    #_ : ℕ → Expr