strictness, ci

[minfp.git] / int.icl

diff --git a/int.icl b/int.icl
index 4cf6b78..f096200 100644 (file)
--- a/int.icl
+++ b/int.icl
@@ -1,11 +1,11 @@
 implementation module int
 
 import StdEnv
-
 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
@@ -13,66 +13,37 @@ import Control.Monad.Trans
 
 import ast
 
-int :: Expression -> Either [String] Value
-int e = evalStateT (eval e >>= printer) preamble
-
-err :: String -> Eval a
-err e = liftT (Left [e])
-
-:: Eval a :== StateT EvalState (Either [String]) a
-:: EvalState :== [([Char], Value)]
-preamble =
-       [(['if'], Func 3 [] (Builtin ['if']))
-       ,(['eq'], Func 2 [] (Builtin ['eq']))
-       ,(['mul'], Func 2 [] (Builtin ['mul']))
-       ,(['div'], Func 2 [] (Builtin ['div']))
-       ,(['add'], Func 2 [] (Builtin ['add']))
-       ,(['sub'], Func 2 [] (Builtin ['sub']))
+:: Eval a :== StateT [([Char], Value)] (Either [String]) a
+
+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))
        ]
-
-sub :: [Char] Expression Expression -> Expression
-sub ident subst (Let v a b rest)
-       = Let v a (if (isMember ident a) b (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
-
-printer :: Value -> Eval Value
-printer (Func 0 args body) = eval (body args) >>= printer
-printer a = pure a
+where
+       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 as body rest)
-       =   modify (\vs->[(ident, Func (length as) [] \e->zipSt sub as e body):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 (err ("Variable " +++ toString v +++ " not found")) pure
+eval (Var v) = gets (lookup v) >>= maybe (liftT (Left [toString v +++ " not found"])) pure
+eval (Lambda a b) = pure (Lambda` a b)
 eval (App e1 e2) = eval e1 >>= \v->case v of
-       (Func 0 a b) = err ("Saturated function: : " +++ toString e1)
-       (Func n as b) = pure (Func (n-1) (as ++ [e2]) b)
-       _ = err ("Cannot apply " +++ toString e2 +++ " to " +++ toString e1)
-eval (Lambda a b) = pure (Func 1 [] (\[arg]->sub a arg b))
-eval (Builtin i as) = case (i, as) of
-       (['if'], [p,t,e]) = eval p >>= printer >>= \v->case v of
-               Bool v = eval (if v t e)
-//             _ = err ("first argument of if must be a bool but is " +++ toString v)
-       (['add'], [l,r]) = eval l >>= printer >>= \l->eval r >>= printer >>= \r->case (l,r) of
-               (Int a, Int b) = pure (Int (a + b))
-//             _ = err "add only defined for integers"
-       (['sub'], [l,r]) = eval l >>= printer >>= \l->eval r >>= printer >>= \r->case (l,r) of
-               (Int a, Int b) = pure (Int (a - b))
-//             _ = err "sub only defined for integers"
-       (['mul'], [l,r]) = eval l >>= printer >>= \l->eval r >>= printer >>= \r->case (l,r) of
-               (Int a, Int b) = pure (Int (a * b))
-//             _ = err "mul only defined for integers"
-       (['div'], [l,r]) = eval l >>= \l->eval r >>= \r->case (l,r) of
-               (Int a, Int b) = pure (Int (a / b))
-//             _ = err "div only defined for integers"
-       (['eq'], [l,r]) = eval l >>= printer >>= \l->eval r >>= printer >>= \r->case (l,r) of
-               (Int a, Int b) = pure (Bool (a == b))
-//             _ = err "eq only defined for integers"
+       (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