Basic expression parsing

1 files changed, 24 insertions, 0 deletions

diff --git a/src/expr.hs b/src/expr.hs
new file mode 100644
index 0000000..3cada63
--- /dev/null
+++ b/src/expr.hs
@@ -0,0 +1,24 @@
+module Expr where
+
+-- data X = Expr | Imag | Matrix
+
+data Expr   = Expr Term Expr     | ExprSingle Term
+data Term   = Term Factor Term   | TermSingle Factor
+data Factor = Factor Base Factor | FactorSingle Base
+data Base   = Base Expr          | BaseSingle Float
+
+instance Show Expr where
+    show (ExprSingle t) = show t
+    show (Expr t e) = show t ++ " + " ++ show e
+
+instance Show Term where
+    show (TermSingle f) = show f
+    show (Term f t) = show f ++ " * " ++ show t
+
+instance Show Factor where
+    show (FactorSingle b) = show b
+    show (Factor b f) = show b ++ " ^ " ++ show f
+
+instance Show Base where
+    show (BaseSingle x) = show x
+    show (Base e) = "( " ++ show e ++ " )"