Add integer and strings to the language

src/Language/Bergamot/Latex.purs

@@ -26,6 +26,8 @@ instance toLatexExpr :: ToLatex k => ToLatex (Expr k) where
     toLatex (Atom "snd" (t : Nil)) = "\\text{snd}\\ " <> toLatex t
     toLatex (Atom s xs) = "\\text{" <> s <> "}(" <> intercalate ", " (toLatex <$> xs) <> ")"
     toLatex (Var x) = toLatex x
+    toLatex (IntLit i) = show i
+    toLatex (StringLit s) = "\"" <> s <> "\""
 
 instance toLatexRule :: ToLatex k => ToLatex (Rule k) where
     toLatex (MkRule {head, tail}) = "\\cfrac{" <> intercalate "\\quad " (toLatex <$> tail) <> "}{" <> toLatex head <> "}"

src/Language/Bergamot/Syntax.purs

@@ -10,6 +10,8 @@ import Data.List (List(..), (:))
 
 data Expr v
     = Var v
+    | IntLit Int
+    | StringLit String
     | Atom String (List (Expr v))
 
 derive instance Eq v => Eq (Expr v)
@@ -28,10 +30,14 @@ instance UnificationVariable IntVar where
 instance UnificationVariable k => Unifiable k Expr where
     variable = Var
     squash (Var f) = f
+    squash (IntLit i) = IntLit i
+    squash (StringLit s) = StringLit s
     squash (Atom name args) = Atom name $ squash <$> args
     alongside (Var k1) (Var k2) = Var (Merge k1 k2)
     alongside (Var k) f = Var (Store k f)
     alongside f (Var k) = Var (Store k f)
+    alongside (IntLit i1) (IntLit i2) | i1 == i2 = IntLit i1
+    alongside (StringLit s1) (StringLit s2) | s1 == s2 = StringLit s1
     alongside (Atom n1 _) (Atom n2 _) | n1 /= n2 = Var Fail
     alongside (Atom n1 args1) (Atom _ args2) = Atom n1 $ combine args1 args2
         where
@@ -39,3 +45,4 @@ instance UnificationVariable k => Unifiable k Expr where
           combine (_:_) Nil = (Var Fail) : Nil
           combine Nil (_:_) = (Var Fail) : Nil
           combine (x:xs) (y:ys) = alongside x y : combine xs ys
+    alongside _ _ = Var Fail