From 97719af3b544b9fae80e886bf6a49c51b4a320a9 Mon Sep 17 00:00:00 2001
From: Michael Andreen <harv@ruin.nu>
Date: Tue, 14 Mar 2006 16:53:17 +0000
Subject: [PATCH] most of the semantics added

---
 Interpret.hs  |  8 ++---
 documentation | 95 +++++++++++++++++----------------------------------
 2 files changed, 33 insertions(+), 70 deletions(-)

diff --git a/Interpret.hs b/Interpret.hs
index 8cf3c1b..c5ef5e0 100644
--- a/Interpret.hs
+++ b/Interpret.hs
@@ -14,10 +14,6 @@ instance Show Value where
 
 type Variables = [Map Ident Value]
 
-inList :: Eq a => a -> [a] -> Bool
-inList _ [] = False
-inList a (x:xs) = if a == x then True else inList a xs
-
 --eval :: (MonadState Variables m) => Exp -> m Value
 eval :: Exp -> StateT Variables IO Value
 eval (EBool b) = return (VBool b)
@@ -27,7 +23,7 @@ eval (EAss i e) = setVariableValue i e
 eval (BiOpExp e o e') = do
 	v <- eval e
 	v'<- eval e'
-	if inList o [Eq,NEq] then return $ opE o v v'
+	if elem o [Eq,NEq] then return $ opE o v v'
 		else let (VInt n1) = v in let (VInt n2) = v' in return $ op o n1 n2
 eval (EPost i o) = do
 	(VInt n) <- getVariableValue i
@@ -49,7 +45,7 @@ eval EReadB = do
 getWord :: IO String
 getWord =  do
 	c <- getChar
-	if inList c [' ', '\n', '\t', '\r']
+	if elem c [' ', '\n', '\t', '\r']
 		then return ""
 		else do
 			l <- getWord
diff --git a/documentation b/documentation
index bbb604f..c3ac4e0 100644
--- a/documentation
+++ b/documentation
@@ -13,131 +13,98 @@ typing rules
 ++++++++++++
 
 
-(t is used for types, T is the context, and + is used for in)
+(v is used for values, e for expressions, s for statements, c is the context)
 
 
-[Eq, NEq]
+[Eq, NEq, Plus, Minus, Times, Div, Lt, ELt, Gt, EGt]
 
-T+ e1 Eq e2:bool  <=  T+ e1:t  &  T+ e2:t
-
-If e1 and e2 are of the same type, then Eq or NEq return bool
-
-
-[Plus, Minus, Times, Div]
-
-T+ e1 Plus e2:int  <=  T+ e1:int  &  T+ e2:int
-
-The operators Plus/Minus/Times/Div return int if both operands are ints
-
-
-[Lt, ELt, Gt, EGt]
-
-T+ e1 Lt e2:bool  <=  T+ e1:int  &  T+ e2:int
-
-The operators Lt/ELt/Gt/EGt return bool if both operands are ints
+<e1 o e2,c> => <v,c''> <= <e1,c> => <v1,c'>  <e2,c'> => <v2,c''> v is the result of using operator o on v1 and v2
 
 
 [Assignment]
 
-T+ i := e:t  <=  i:t in T  &  T+ e:t
-
-The assignemnt of e to i returns type t if both i and e have type t.
+<i := e,c> => c'[i -> v] <= <e,c> => <v,c'>
 
+Assign the value v to i in the first scope i is found in.
 
 [ENeg]
 
-T+ ENeg e:int  <=  T+ e:int
+<e,c> => <-v,c'> <= <e,c> => <v,c'>
 
-ENeg e returns int if e is of type int
 
 [ENot]
 
-T+ ENot e:bool  <=  e:bool
-
-ENot e returns bool if e is of type bool
+<e,c> => <not v,c'> <= <e,c> => <v,c'>
 
 [EVar]
 
-T+ i:t <= i:t in T
-
-i has type t if i is defined in the context with type t.
+<i,c> => <c(i),c>
 
 [EInt]
 
-T+ n:int
-
-n has type int
+<n,c> => <n,c>
 
 [EBool]
 
-T+ b:bool
-
-b has type bool
-
-[EReadI]
-
-T+ n:int
+<b,c> => <b,c>
 
-EReadI returns an int
+[EReadI,EReadB]
 
-[EReadB]
-
-T+ b:bool
-
-EReadB returns a bool
+<c> => <v,c'> <= <IO,c> => <v,c'>
 
 [EPost]
 
-T+ EPost i:int <= i:int in T
+<i,c> => <v,c[i->v']> <= c(i) => v, v±1 => v'
 
-EPost i is of type int if i is defined in T with type int.
+Look up the variable, add/subtract 1 from the value then return the old value and context with modified value
 
 [SExp]
 
-T+ e   <=  T+ e:t
+<e,c> => c' <= <e,c> => <v,c'>
 
 [SBlock]
 
-T+ s;SBlock ss <= T+ s => T' , T'+ ss => T''
+<SBlock s,c> => c'''  <= push(c) => c' <s,c'> => c'' pop(c'') => c'''
+
+Push a new scope onto the context, execute the statements in this context and the pop the scope from the context
 
-the first statment s, in the block, is typechecked in the context T and returns the context T', the rest of the block is then recursively typeckecked in the context T' 
+[SEQ]
 
+<s1;s2,c> => c'' <= <s1,c> => c' <s2,c'> => c''
 
 [SIf]
 
-T+ if e then s1 else s2  <=  T+ e:bool  &  T+ s1  &  T+ s2
+<if e s1 s2,c> => pop(c''') <= <e,c> => <true,c'> push(c') <s1,c''> => c'''
 
-if e is of type bool and s1 and and s2 typechecks in the context T, then the same context is returned
+<if e s1 s2,c> => pop(c''') <= <e,c> => <false,c'> push(c') <s2,c''> => c'''
 
 
 [SWhile]
 
-T+ while e do s  <=  T+ e:bool  &  T+ s
-
-If e is of type bool and s typechecks in context T then the same context is returned
+<while e s,c> => c' => <e,c> => <false,c'>
 
+<while e s,c> => pop(c''') => <e,c> => <true,c'> push(c') => c'' <s,c''> => c'''
 
 
 [SDecl]
 
-T+ t i = e => T,i:t  <=  i not in T  &  e:t 
+<i := e,c> => c'[i->v] <= <e,c> => <v,c'>
 
-if i and e are of the same type and i is not declared in the current scope then i is added with type t to the context.
+Adds i with value v to the current scope in the context
 
 [SDeclD]
 
-T+ t i => T,i:t  <=  i not in T
+<int i,c> => c[i->0]
+<bool i,c> => c[i->false]
 
-if i is not declared in the current scope, then i is added to the context with type t
+Adds i with default value in the current scope
 
 [SNoop]
 
-T+ s
+<SNoop,c> => c
 
 SNoops does nothing so the same context is returned
 
 [SPrint]
 
-T+ e <= T+ e:t
-
-if e has type t then SPrint returns the same context
+<e,c> => c'' <= <e,c> => <v,c'> <IO v,c'>  => c''
-- 
2.39.2