Add unsigned int types

src/libasr/ASR.asdl

@@ -237,6 +237,10 @@ expr
     | IntegerUnaryMinus(expr arg, ttype type, expr? value)
     | IntegerCompare(expr left, cmpop op, expr right, ttype type, expr? value)
     | IntegerBinOp(expr left, binop op, expr right, ttype type, expr? value)
+    | UnsignedIntegerConstant(float re, float im, ttype type)
+    | UnsignedIntegerUnaryMinus(expr arg, ttype type, expr? value)
+    | UnsignedIntegerCompare(expr left, cmpop op, expr right, ttype type, expr? value)
+    | UnsignedIntegerBinOp(expr left, binop op, expr right, ttype type, expr? value)
     | RealConstant(float r, ttype type)
     | RealUnaryMinus(expr arg, ttype type, expr? value)
     | RealCompare(expr left, cmpop op, expr right, ttype type, expr? value)
@@ -346,6 +350,7 @@ expr
 
 ttype
     = Integer(int kind, dimension* dims)
+    | UnsignedInteger(int kind, dimension* dims)
     | Real(int kind, dimension* dims)
     | Complex(int kind, dimension* dims)
     | Character(int kind, int len, expr? len_expr, dimension* dims)
@@ -402,6 +407,8 @@ cast_kind
     | RealToCharacter
     | IntegerToCharacter
     | LogicalToCharacter
+    | UnsignedIntegerToInteger
+    | IntegerToUnsignedInteger
 
 dimension = (expr? start, expr? length)
 

src/runtime/lpython/lpython.py

@@ -6,7 +6,7 @@
 from goto import with_goto
 
 # TODO: this does not seem to restrict other imports
-__slots__ = ["i8", "i16", "i32", "i64", "f32", "f64", "c32", "c64", "CPtr",
+__slots__ = ["i8", "i16", "i32", "i64", "u8", "u16", "u32", "u64", "f32", "f64", "c32", "c64", "CPtr",
         "overload", "ccall", "TypeVar", "pointer", "c_p_pointer", "Pointer",
         "p_c_pointer", "vectorize", "inline", "Union", "static", "with_goto",
         "packed", "Const", "sizeof", "ccallable", "ccallback", "Callable"]
@@ -18,6 +18,10 @@
     "i16": int,
     "i32": int,
     "i64": int,
+    "u8": lambda x: x,
+    "u16": lambda x: x,
+    "u32": lambda x: x,
+    "u64": lambda x: x,
     "f32": float,
     "f64": float,
     "c32": complex,