Week5 Ex 1, 2, 3 ,4

cis194/week5/tien/.gitignore

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+.stack-work/
+tien.cabal
+*~

cis194/week5/tien/ChangeLog.md

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+# Changelog for tien
+
+## Unreleased changes

cis194/week5/tien/LICENSE

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+Copyright Tien (c) 2019
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Tien nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

cis194/week5/tien/README.md

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+# tien

cis194/week5/tien/Setup.hs

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+import Distribution.Simple
+main = defaultMain

cis194/week5/tien/app/Main.hs

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+module Main where
+
+
+main :: IO ()
+main = putStr "main hs"

cis194/week5/tien/package.yaml

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+name:                tien
+version:             0.1.0.0
+github:              "tienwei/tien"
+license:             BSD3
+author:              "Tien"
+maintainer:          "tienlindev@gmail.com"
+copyright:           "2019 Tien"
+
+extra-source-files:
+- README.md
+- ChangeLog.md
+
+# Metadata used when publishing your package
+# synopsis:            Short description of your package
+# category:            Web
+
+# To avoid duplicated efforts in documentation and dealing with the
+# complications of embedding Haddock markup inside cabal files, it is
+# common to point users to the README.md file.
+description:         Please see the README on GitHub at <https://github.com/tienwei/tien#readme>
+
+dependencies:
+- base >= 4.7 && < 5
+- hspec
+
+library:
+  source-dirs: src
+
+executables:
+  tien-exe:
+    main:                Main.hs
+    source-dirs:         app
+    ghc-options:
+    - -threaded
+    - -rtsopts
+    - -with-rtsopts=-N
+    dependencies:
+    - tien
+
+tests:
+  tien-test:
+    main:                CalcSpec.hs
+    source-dirs:         test
+    ghc-options:
+    - -threaded
+    - -rtsopts
+    - -with-rtsopts=-N
+    dependencies:
+    - tien

cis194/week5/tien/src/Calc.hs

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+{-# OPTIONS_GHC -Wall #-}
+{-# LANGUAGE ViewPatterns #-}
+
+module Calc where
+
+import           ExprT
+import           Parser
+
+-- Exercise 1 --
+eval :: ExprT -> Integer
+eval (Lit a)   = a
+eval (Add a b) = eval a + eval b
+eval (Mul a b) = eval a * eval b
+
+-- Exercise 2 --
+evalStr :: String -> Maybe Integer
+evalStr (parseExp Lit Add Mul -> justExpr) = eval <$> justExpr
+
+-- Exercise 3 --
+class Expr a where
+  lit :: Integer -> a
+  add :: a -> a -> a
+  mul :: a -> a -> a
+
+instance Expr ExprT where
+  lit a = Lit a
+  add a b = Add a b
+  mul a b = Mul a b
+
+-- Exercise 4 --
+newtype MinMax =
+  MinMax Integer
+  deriving (Eq, Show)
+
+newtype Mod7 =
+  Mod7 Integer
+  deriving (Eq, Show)
+
+instance Expr Integer where
+  lit a = a
+  add a b = a + b
+  mul a b = a * b
+
+instance Expr Bool where
+  lit a = a > 0
+  add a b = a || b
+  mul a b = a && b
+
+instance Expr MinMax where
+  lit a = MinMax a
+  add (MinMax a) (MinMax b) = MinMax $ max a b
+  mul (MinMax a) (MinMax b) = MinMax $ min a b
+
+instance Expr Mod7 where
+  lit a = Mod7 $ mod 7 a
+  add (Mod7 a) (Mod7 b) = Mod7 $ lit a + lit b
+  mul (Mod7 a) (Mod7 b) = Mod7 $ lit a * lit b
+
+testExp :: Expr a => Maybe a
+testExp = parseExp lit add mul "(3 * -4) + 5"
+
+testInteger = testExp :: Maybe Integer
+
+testBool = testExp :: Maybe Bool
+
+testMM = testExp :: Maybe MinMax
+
+testSat = testExp :: Maybe Mod7

cis194/week5/tien/src/ExprT.hs

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+module ExprT where
+
+data ExprT = Lit Integer
+           | Add ExprT ExprT
+           | Mul ExprT ExprT
+  deriving (Show, Eq)

cis194/week5/tien/src/Parser.hs

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+-- Applicative parser for infix arithmetic expressions without any
+-- dependency on hackage. Builds an explicit representation of the
+-- syntax tree to fold over using client-supplied semantics.
+module Parser (parseExp) where
+import Control.Applicative hiding (Const)
+import Control.Arrow
+import Data.Char
+import Data.Monoid
+import Data.List (foldl')
+
+-- Building block of a computation with some state of type @s@
+-- threaded through it, possibly resulting in a value of type @r@
+-- along with some updated state.
+newtype State s r = State (s -> Maybe (r, s))
+
+-- Expressions
+data Expr = Const Integer
+          | Add Expr Expr
+          | Mul Expr Expr
+            deriving Show
+
+instance Functor (State s) where
+    fmap f (State g) = State $ fmap (first f) . g
+
+instance Applicative (State s) where
+    pure x = State $ \s -> Just (x, s)
+    State f <*> State g = State $ \s ->
+                          case f s of
+                            Nothing -> Nothing
+                            Just (r, s') -> fmap (first r) . g $ s'
+
+instance Alternative (State s) where
+    empty = State $ const Nothing
+    State f <|> State g = State $ \s -> maybe (g s) Just (f s)
+
+-- A parser threads some 'String' state through a computation that
+-- produces some value of type @a@.
+type Parser a = State String a
+
+-- Parse one numerical digit.
+digit :: Parser Integer
+digit = State $ parseDigit
+    where parseDigit [] = Nothing
+          parseDigit s@(c:cs)
+              | isDigit c = Just (fromIntegral $ digitToInt c, cs)
+              | otherwise = Nothing
+
+-- Parse an integer. The integer may be prefixed with a negative sign.
+num :: Parser Integer
+num = maybe id (const negate) <$> optional (char '-') <*> (toInteger <$> some digit)
+    where toInteger = foldl' ((+) . (* 10)) 0
+
+-- Parse a single white space character.
+space :: Parser ()
+space = State $ parseSpace
+    where parseSpace [] = Nothing
+          parseSpace s@(c:cs)
+              | isSpace c = Just ((), cs)
+              | otherwise = Nothing
+
+-- Consume zero or more white space characters.
+eatSpace :: Parser ()
+eatSpace = const () <$> many space
+
+-- Parse a specific character.
+char :: Char -> Parser Char
+char c = State parseChar
+    where parseChar [] = Nothing
+          parseChar (x:xs) | x == c = Just (c, xs)
+                           | otherwise = Nothing
+
+-- Parse one of our two supported operator symbols.
+op :: Parser (Expr -> Expr -> Expr)
+op = const Add <$> (char '+') <|> const Mul <$> (char '*')
+
+-- Succeed only if the end of the input has been reached.
+eof :: Parser ()
+eof = State parseEof
+    where parseEof [] = Just ((),[])
+          parseEof _  = Nothing
+
+-- Parse an infix arithmetic expression consisting of integers, plus
+-- signs, multiplication signs, and parentheses.
+parseExpr :: Parser Expr
+parseExpr = eatSpace *>
+            ((buildOp <$> nonOp <*> (eatSpace *> op) <*> parseExpr) <|> nonOp)
+    where buildOp x op y = x `op` y
+          nonOp = char '(' *> parseExpr <* char ')' <|> Const <$> num
+
+-- Run a parser over a 'String' returning the parsed value and the
+-- remaining 'String' data.
+execParser :: Parser a -> String -> Maybe (a, String)
+execParser (State f) = f
+
+-- Run a parser over a 'String' returning the parsed value.
+evalParser :: Parser a -> String -> Maybe a
+evalParser = (fmap fst .) . execParser
+
+-- Parse an arithmetic expression using the supplied semantics for
+-- integral constants, addition, and multiplication.
+parseExp :: (Integer -> a) -> (a -> a -> a) -> (a -> a -> a) -> String -> Maybe a
+parseExp con add mul = (convert <$>) . evalParser (parseExpr <* eof)
+    where convert (Const x) = con x
+          convert (Add x y) = add (convert x) (convert y)
+          convert (Mul x y) = mul (convert x) (convert y)

cis194/week5/tien/src/StackVM.hs

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+module StackVM (StackVal(..), StackExp(..), Stack, Program, stackVM) where
+
+-- Values that may appear in the stack. Such a value will also be
+-- returned by the stackVM program execution function.
+data StackVal = IVal Integer | BVal Bool | Void deriving Show
+
+-- The various expressions our VM understands.
+data StackExp = PushI Integer
+              | PushB Bool
+              | Add
+              | Mul
+              | And
+              | Or
+                deriving Show
+
+type Stack   = [StackVal]
+type Program = [StackExp]
+
+-- Execute the given program. Returns either an error message or the
+-- value on top of the stack after execution.
+stackVM :: Program -> Either String StackVal
+stackVM = execute []
+
+errType :: String -> Either String a
+errType op = Left $ "Encountered '" ++ op ++ "' opcode with ill-typed stack."
+
+errUnderflow :: String -> Either String a
+errUnderflow op = Left $ "Stack underflow with '" ++ op ++ "' opcode."
+
+-- Execute a program against a given stack.
+execute :: Stack -> Program -> Either String StackVal
+execute [] []                               = Right Void
+execute (s:_) []                            = Right s
+
+execute s (PushI x : xs)                    = execute (IVal x : s) xs
+execute s (PushB x : xs)                    = execute (BVal x : s) xs
+
+execute (IVal s1 : IVal s2 : ss) (Add : xs) = execute (s':ss) xs
+    where s' = IVal (s1 + s2)
+execute (_:_:_) (Add:_)                     = errType "Add"
+execute _ (Add:_)                           = errUnderflow "Add"
+
+execute (IVal s1:IVal s2:ss) (Mul : xs)     = execute (s':ss) xs
+    where s' = IVal (s1 * s2)
+execute (_:_:_) (Mul:_)                     = errType "Mul"
+execute _ (Mul:_)                           = errUnderflow "Mul"
+
+execute (BVal s1:BVal s2:ss) (And : xs)     = execute (s':ss) xs
+    where s' = BVal (s1 && s2)
+execute (_:_:_) (And:_)                     = errType "And"
+execute _ (And:_)                           = errUnderflow "And"
+
+execute (BVal s1 : BVal s2 : ss) (Or : xs)  = execute (s':ss) xs
+    where s' = BVal (s1 || s2)
+execute (_:_:_) (Or:_)                      = errType "Or"
+execute _ (Or:_)                            = errUnderflow "Or"
+
+test = stackVM [PushI 3, PushI 5, Add]