wip: port REPL from minilang

1 files changed, 7 insertions, 29 deletions

diff --git a/lambda-calcul/haskell/src/Minilang/Lambda/Eval.hs b/lambda-calcul/haskell/src/Minilang/Lambda/Eval.hs
index cbbdc51..58f8ba6 100644
--- a/lambda-calcul/haskell/src/Minilang/Lambda/Eval.hs
+++ b/lambda-calcul/haskell/src/Minilang/Lambda/Eval.hs
@@ -9,36 +9,14 @@ data Term
   | App Term Term
   deriving (Show, Read, Eq)
 
-type Env = [(Text, Value)]
+type Env = [(Text, Term)]
 
-data Value
-  = V Text
-  | Abs Text Term Env -- a closure, ie. lambda with its captured environment
-  | Ap Value Value
-  deriving (Show, Read, Eq)
+newEnv :: Env
+newEnv = []
 
 -- call-by-value evaluator
-eval :: Term -> Env -> Value
-eval (Var x) env = case lookup x env of
-  Just v -> v -- we do not need to eval v again
-  Nothing -> V x -- x is not bound in env
-eval (Lam x body) env = Abs x body env
-eval (App f a) env =
-  -- we need to force evaluation of the argument
-  -- because haskell's default semantics is non-strict
-  -- so if a' is never used, it will not be evaluated!
-  let a' = eval a env
-   in seq a' $ case eval f env of
-        Abs x body env' -> eval body ((x, a') : env')
-        f' -> Ap f' a'
+eval :: Term -> Env -> Term
+eval = undefined
 
-evalNeed :: Term -> Env -> Value
-evalNeed (Var x) env = case lookup x env of
-  Just v -> v
-  Nothing -> V x
-evalNeed (Lam x body) env = Abs x body env
-evalNeed (App f a) env =
-  let a' = eval a env
-   in case evalNeed f env of
-        Abs x body env' -> evalNeed body ((x, a') : env')
-        f' -> Ap f' a'
+evalNeed :: Term -> Env -> Term
+evalNeed = undefined