strictness, ci

[minfp.git] / int.icl

diff --git a/int.icl b/int.icl
index eec77c4..f096200 100644 (file)
--- a/int.icl
+++ b/int.icl
@@ -5,6 +5,7 @@ import Data.Either
 import Data.Functor
 import Data.Maybe
 import Data.List
+import Data.Tuple
 import Control.Applicative
 import Control.Monad
 import Control.Monad.State
@@ -12,35 +13,37 @@ import Control.Monad.Trans
 
 import ast
 
-:: Eval a :== StateT EvalState (Either [String]) a
-:: EvalState :== [([Char], Value)]
+:: Eval a :== StateT [([Char], Value)] (Either [String]) a
 
-int :: Expression -> Either [String] Value
-int e = evalStateT (eval e) preamble
-
-preamble =
-       [(['_if'], Func \i->pure (Func \t->pure (Func \e->eval i >>= \(Bool b)->if b (eval t) (eval e))))
-       ,(['_eq'],  binop \(Int i) (Int j)->Bool (i==j))
-       ,(['_sub'], binop \(Int i) (Int j)->Int  (i-j))
-       ,(['_add'], binop \(Int i) (Int j)->Int  (i+j))
-       ,(['_mul'], binop \(Int i) (Int j)->Int  (i*j))
-       ,(['_div'], binop \(Int i) (Int j)->Int  (i/j))
+int :: !Expression -> Either [String] Value
+int e = evalStateT (eval e)
+       [(['_if'], Builtin \i->pure (Lit (Builtin \t->pure (Lit (Builtin \e->
+               eval i >>= \(Bool b)->pure (if b t e))))))
+       ,(['_eq'],  binop \(Int i) (Int j)->Bool (i == j))
+       ,(['_sub'], binop \(Int i) (Int j)->Int  (i - j))
+       ,(['_add'], binop \(Int i) (Int j)->Int  (i + j))
+       ,(['_mul'], binop \(Int i) (Int j)->Int  (i * j))
+       ,(['_div'], binop \(Int i) (Int j)->Int  (i / j))
        ]
 where
-       binop op = Func \l->pure (Func \r->op <$> eval l <*> eval r)
-
-sub :: [Char] Expression Expression -> Expression
-sub ident subst (Let v b rest) = Let v (sub ident subst b) (if (v == ident) rest (sub ident subst rest))
-sub ident subst (Var v)
-       | ident == v = subst
-sub ident subst (App e1 e2) = App (sub ident subst e1) (sub ident subst e2)
-sub ident subst (Lambda v b)
-       | ident <> v = Lambda v (sub ident b subst)
-sub _ _ x = x
+       binop :: (Value Value -> Value) -> Value
+       binop op = Builtin \l->pure (Lit (Builtin \r->(o) Lit o op <$> eval l <*> eval r))
 
 eval :: Expression -> Eval Value
-eval (Let ident body rest) = eval body >>= \v->modify (\vs->[(ident, v):vs]) >>| eval rest
+eval (Let ns rest) = sequence [eval v >>= \v->modify (\vs->[(n, v):vs])\\(n, v)<-ns] >>| eval rest
 eval (Lit v) = pure v
 eval (Var v) = gets (lookup v) >>= maybe (liftT (Left [toString v +++ " not found"])) pure
-eval (App e1 e2) = eval e1 >>= \(Func v)->v e2
-eval (Lambda a b) = pure (Func \arg->eval (sub a arg b))
+eval (Lambda a b) = pure (Lambda` a b)
+eval (App e1 e2) = eval e1 >>= \v->case v of
+       (Lambda` v b) = eval (sub v e2 b)
+       (Builtin f) = f e2 >>= eval
+where
+       sub :: [Char] Expression Expression -> Expression
+       sub i subs (Let ns rest)
+               | not (isMember i (map fst ns)) = Let (fmap (sub i subs) <$> ns) (sub i subs rest)
+       sub i subs (Var v)
+               | i == v = subs
+       sub i subs (App e1 e2) = App (sub i subs e1) (sub i subs e2)
+       sub i subs (Lambda v b)
+               | i <> v = Lambda v (sub i subs b)
+       sub _ _ x = x