deque-blog’s gists

deque-blog / dsl_arithmetic_1_eval.hs

Created January 16, 2017 20:04

	type Env = Map.Map String Int

	eval :: Env -> Expr -> Int
	eval env (Cst n) = n
	eval env (Var v) = env Map.! v
	eval env (Op Add xs) = sum $ map (eval env) xs
	eval env (Op Mul xs) = product $ map (eval env) xs

deque-blog / dsl_arithmetic_1_optimize.hs

Last active January 21, 2017 21:09

	optimize :: Expr -> Expr
	optimize op@(Op Add ys) = optimizeOp Add (map optimize ys) 0 (+)
	optimize op@(Op Mul ys)
	\| not (null (dropWhile (/= cst 0) xs)) = cst 0
	\| otherwise = optimizeOp Mul xs 1 (*)
	where xs = map optimize ys
	optimize e = e

	optimizeOp :: OpType -> [Expr] -> Int -> (Int -> Int -> Int) -> Expr
	optimizeOp opType xs neutral combine =

deque-blog / dsl_arithmetic_1_partial.hs

Created January 16, 2017 20:20

	partial :: Env -> Expr -> Expr
	partial env e@(Var v) =
	case Map.lookup v env of
	Nothing -> e
	Just n -> cst n
	partial env (Op opType xs) = Op opType (map (partial env) xs)
	partial env e = e

deque-blog / dsl_arithmetic_1_eval_as_partial.hs

Created January 16, 2017 20:26

	dependencies :: Expr -> Set.Set Id
	dependencies (Var v) = Set.singleton v
	dependencies (Op _ xs) = foldl1' Set.union (map dependencies xs)
	dependencies e = Set.empty

	eval' :: Env -> Expr -> Int
	eval' env e =
	case optimize (partial env e) of
	Cst n -> n
	e -> error $ "Missing vars: " ++ show (dependencies e)

deque-blog / dsl_arithmetic_1_optimize_test.hs

Created January 17, 2017 17:09

deque-blog / dsl_arithmetic_1_eval_as_partial_test.hs

Created January 17, 2017 17:14

deque-blog / dsl_arithmetic_1_eval_as_partial_test_2.hs

Created January 17, 2017 17:18

deque-blog / dsl_arithmetic_1_eval_test.hs

Created January 17, 2017 17:23

deque-blog / dsl_arithmetic_1_enhanced_eval_test.hs

Created January 17, 2017 17:37

	> let e = add [ cst(1)
	, cst(2)
	, mul [cst(0), var("x"), var("y")]
	, mul [cst(1), var("y"), cst(2)]
	, add [cst(0), var("x") ]]

	> let env = Map.fromList [("x", 1)]

	> eval' env e
	*** Exception: Missing vars: fromList ["y"]

deque-blog / dsl_arithmetic_2_expr.hs

Created January 18, 2017 20:38

	type Id = String
	data OpType = Add \| Mul deriving (Show, Eq, Ord)

	data ExprR r
	= Cst Int
	\| Var Id
	\| Op OpType [r]
	deriving (Show, Eq, Ord)