interpreter seems to work

[proglang.git] / documentation

diff --git a/documentation b/documentation
index 28be8953c583ac46e7fc73b3998982312167a67d..269e93139c744f83508a076206088f76e7634b81 100644 (file)
--- a/documentation
+++ b/documentation
@@ -1,18 +1,86 @@
 ####### DOCUMENTATIATOIAITAT ION ########
 
 
-a simple c-like language with support for if/else-statements, while-loops and the standard arithmetic (+, -, /, *) and comparison expressions (<, >, <=, >=, ==, !=). also, post increase/decrease expressions (++, --) are supported. Assignments are allowed in expressions, but they are only allowed on the right side of arithmetic/comparision operators if they are put inside parenthesis
+Files:
+Typechecker.hs: Simple modification of the bnfc-generated Testsyntax which calls the type-checking functions.
+
+Typecheck.hs: Contains the type-checking functions typeCheckExp, typeCheckVar and typeCheckStm and some utility functions, responsible for the entire type-checking process.
+
+Abssyntax.hs, Parsyntax.y, Lexsyntax.x,ErrM.hs,Printsyntax.hs,Skelsyntax.hs: The files generated by bnfc, only modification is the removal of the Bool type in Abssyntx.hs so haskell's internal type can be used.
+
+
+typing rules
+++++++++++++
+
+
+(t is little tau, T is large tau, E is 'in', and + is that other symbol)
+
+
+
+[Eq, Neq]
+
+e:bool  <=  e1:t  &  e2:t
+where e is e1 Eq e2.
+
+
+[Plus, Minus, Times, Div]
+
+e:int  <=  e1:int  &  e2:int
+where e is e1 Plus e2.
+
+
+[Lt, ELt, Gt, EGt]
+
+e:bool  <=  e1:int  &  e2:int
+where e is e1 Lt e2.
+
+
+[Assignment]
+
+T+ i := e:t  <=  i:t E T  &  T+ e:t
+where the assignment is identifier i = expression e.
+
+
+[ExpT]
+
+u,e:t  <=  e:t  &  u:t
+where the expression is type u expression e.
+
+
+[ENeg]
+
+e:int  <=  e:int
+
+
+[ENot]
+
+e:bool  <=  e:bool
+
+
+[SExp, SBlock]
+
+S:NoType  <=  e:t
+
+
+[SIf]
+
+T+ if e then s1 else s2  <=  T+ e:bool  &  T+ s1  &  T+ s2
+
+
+[SWhile]
+
+T+ while e do s  <=  T+ e:bool  &  T+ s
+
+
+[SDecl]
+
+T+ i:t => T', i:t  <=  i!ET  &  e:t  &  u:t
+
+(Type u Ident i = Exp e)
+
 
 
-data types:
-integers and booleans.
 
-comments:
-// and /* */ comments are allowed.
 
-(For compilation to work the Bool type in Abssyntax has to be removed so the internal haskell type is used)
 
-shift/reduce conflicts:
 
-if with else: 1 conflict
-An if statement before the else could be reduced to an if statement lacking the else, but the correct thing is to shift it onto the stack.