1 files changed, 42 insertions, 0 deletions

diff --git a/src/Base.hs b/src/Base.hs
new file mode 100644
index 0000000..08131e8
--- /dev/null
+++ b/src/Base.hs
@@ -0,0 +1,42 @@
+module Base (Expr (..)
+            , Env (..)
+            , Function (..)
+            ) where
+
+import           Data.IORef
+
+-- TODO: use LispNumber (src/Operators.hs) here instead of IntLiteral and FloatLiteral
+-- TODO: add character literals: \#a \#b \#c \#space \#newline
+-- TODO: add support for complex numbers, oct and hex numbers
+data Expr = List [Expr]
+          | Vector [Expr]
+          | DottedList [Expr] Expr
+          | StringLiteral String
+          | IntLiteral Integer
+          | FloatLiteral Double
+          | BoolLiteral Bool
+          | Id String
+          deriving (Eq)
+
+data Function =
+    Function {
+    params        :: [String]
+    , body        :: Expr
+    , environment :: Env
+    }
+
+type Env = IORef [(String, IORef Expr)]
+
+showLispList :: [Expr] -> String
+showLispList = unwords . map show
+
+instance Show Expr where
+    show (DottedList xs x)   = "(" ++ showLispList xs ++ " . " ++ show x ++ ")"
+    show (List xs)           = "(" ++ showLispList xs ++ ")"
+    show (Vector xs)         = "#(" ++ showLispList xs ++ ")"
+    show (StringLiteral s)   = "\"" ++ s ++ "\""
+    show (IntLiteral n)      = show n
+    show (FloatLiteral n)    = show n
+    show (BoolLiteral True)  = "#t"
+    show (BoolLiteral False) = "#f"
+    show (Id i)              = i