Extract latex generation to a typeclass

src/Language/Bergamot/Latex.purs

@@ -0,0 +1,34 @@
+module Language.Bergamot.Latex where
+
+import Prelude
+
+import Language.Bergamot.Syntax (Expr(..))
+import Language.Bergamot.Rules (Rule(..), ProofTree(..))
+import Data.Foldable (intercalate)
+import Data.List (List(..), (:))
+
+class ToLatex a where
+    toLatex :: a -> String
+
+instance toLatexString :: ToLatex String where
+    toLatex s = s
+
+instance toLatexExpr :: ToLatex k => ToLatex (Expr k) where
+    toLatex (Atom "type" (t1 : t2 : Nil)) = toLatex t1 <> " : " <> toLatex t2
+    toLatex (Atom "int" Nil) = "\\text{int}"
+    toLatex (Atom "string" Nil) = "\\text{string}"
+    toLatex (Atom "prod" (t1 : t2 : Nil)) = toLatex t1 <> "\\times " <> toLatex t2
+    toLatex (Atom "n" Nil) = "n"
+    toLatex (Atom "s" Nil) = "s"
+    toLatex (Atom "plus" (t1 : t2 : Nil)) = toLatex t1 <> " + " <> toLatex t2
+    toLatex (Atom "pair" (t1 : t2 : Nil)) = "(" <> toLatex t1 <> ", " <> toLatex t2 <> ")"
+    toLatex (Atom "fst" (t : Nil)) = "\\text{fst}\\ " <> toLatex t
+    toLatex (Atom "snd" (t : Nil)) = "\\text{snd}\\ " <> toLatex t
+    toLatex (Atom s xs) = "\\text{" <> s <> "}(" <> intercalate ", " (toLatex <$> xs) <> ")"
+    toLatex (Var x) = toLatex x
+
+instance toLatexRule :: ToLatex k => ToLatex (Rule k) where
+    toLatex (MkRule {head, tail}) = "\\cfrac{" <> intercalate "\\quad " (toLatex <$> tail) <> "}{" <> toLatex head <> "}"
+
+instance toLatexTree :: ToLatex k => ToLatex (ProofTree k) where
+    toLatex (MkProofTree {claim, witnesses}) = "\\cfrac{" <> intercalate "\\quad " (toLatex <$> witnesses) <> "}{" <> toLatex claim <> "}"