X-Git-Url: https://git.martlubbers.net/?a=blobdiff_plain;f=expr%2Fshallow.icl;fp=expr%2Fshallow.icl;h=71a3abc22d94d1ff0008c473eab0a699494cca03;hb=938d3406c1e406db293024b9a5710579a0090893;hp=0000000000000000000000000000000000000000;hpb=53817603554125625f3c7d6b4b9ea0dc4a4bdf78;p=clean-tests.git

diff --git a/expr/shallow.icl b/expr/shallow.icl
new file mode 100644
index 0000000..71a3abc
--- /dev/null
+++ b/expr/shallow.icl
@@ -0,0 +1,37 @@
+module shallow
+
+import StdEnv
+import Data.Func
+import Data.Functor
+import Data.Either
+import Data.List
+import Data.Maybe
+import Control.Applicative
+import Control.Monad
+
+:: Expr :==
+	([(String, Int)] -> Either String Int //Evaluator
+	, String)                             //Printer
+
+lit :: Int -> Expr
+lit i = (const $ pure i, toString i)
+
+var :: String -> Expr
+var s =
+	( maybe (Left $ "Undefined variable " +++ s) Right o lookup s
+	, s
+	)
+
+(+.) infixl 6 :: Expr Expr -> Expr
+(+.) (ea, pa) (eb, pb) =
+	( \s->liftM2 (+) (ea s) (eb s)
+	, pa +++ " + " +++ pb
+	)
+
+print :: Expr -> String
+print (_, p) = p
+
+eval :: Expr [(String, Int)]-> Either String Int
+eval (e, _) s = e s
+
+Start = eval (lit 5 +. lit 37) []