####### DOCUMENTATIATOIAITAT ION ########
+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.
-a simple c-like language with support for if/else-statements, while-loops and the standard arithmetic (+, -, /, *) and comparison expressions (<, >, <=, >=, ==, !=). also, increase/decrease expressions (++, --) are supported.
+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.
-data types:
-integers and booleans.
-comments:
-// and /* */ comments are allowed.
+typing rules
+++++++++++++
+(t is used for types, T is the context, and + is used for in)
+[Eq, NEq]
+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]
-examples:
+T+ e1 Lt e2:bool <= T+ e1:int & T+ e2:int
-fib
----
-int n1 = 0;
-int n2 = 1;
-int n = readInt;
+The operators Lt/ELt/Gt/EGt return bool if both operands are ints
-while(n-- > 0){
- int temp = n1+n2;
- n1 = n2;
- n2 = temp;
-}
-print n2;
+[Assignment]
-tests while, decr and 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.
-if
---
-if (readBool) {
- if (readInt < 0)
- print true;
- else
- print false;
-}
+[ENeg]
+T+ ENeg e:int <= T+ e:int
-tests if and if/else.
+ENeg e returns int if e is of type int
+[ENot]
+T+ ENot e:bool <= e:bool
-sum
----
-int n;
-int sum = 0;
-while ((n = readInt) != -1) sum = sum + n;
-print sum;
+ENot e returns bool if e is of type bool
+[EVar]
+T+ i:t <= i:t in T
+i has type t if i is defined in the context with type t.
-var
----
-int a = 3;
-int b = a - 5;
-int c = a + b*7;
-bool d = a == b;
+[EInt]
-tests simple variable operations.
\ No newline at end of file
+T+ n:int
+
+n has type int
+
+[EBool]
+
+T+ b:bool
+
+b has type bool
+
+[EReadI]
+
+T+ n:int
+
+EReadI returns an int
+
+[EReadB]
+
+T+ b:bool
+
+EReadB returns a bool
+
+[EPost]
+
+T+ EPost i:int <= i:int in T
+
+EPost i is of type int if i is defined in T with type int.
+
+[SExp]
+
+T+ e <= T+ e:t
+
+[SBlock]
+
+T+ s;SBlock ss <= T+ s => T' , T'+ ss => T''
+
+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'
+
+
+[SIf]
+
+T+ if e then s1 else s2 <= T+ e:bool & T+ s1 & T+ s2
+
+if e is of type bool and s1 and and s2 typechecks in the context T, then the same context is returned
+
+
+[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
+
+
+
+[SDecl]
+
+T+ t i = e => T,i:t <= i not in T & e:t
+
+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.
+
+[SDeclD]
+
+T+ t i => T,i:t <= i not in T
+
+if i is not declared in the current scope, then i is added to the context with type t
+
+[SNoop]
+
+T+ s
+
+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
projects / proglang.git / blobdiff