Kernel expression

The class Expression is the mother of all expressions in the kernel language. It specifies the prototypes of the methods that must be implemented by all expression subclasses. The subclasses of Expression are:

• Constant: constant (void, boolean, integer, real number, object);^3.1

• Abstraction: functional abstraction (à la $\lambda$-calculus);^3.2

• Application: functional application;

• Local: local name;

• Global: global name;

• IfThenElse: conditional;

• AndOr: non-strict boolean conjunction and disjunction;

• Sequence: sequence of expressions (presumably with side-effects);

• Let: lexical scoping construct;

• Loop: conditional iteration construct;

• ExitWithValue: non-local function exit;

• Definition: definition of a global name with an expression defining it in a global store;

• Parameter: a function's formal parameter (really a pseudo-expression as it is not fully processed as a real expression and is used as a shared type information repository for all occurrences in a function's body of the variable it stands for);

• Assignment: construct to set the value of a local or a global variable;

• NewObject: construct to create a new object;

• FieldUpdate: construct to update the value of an object's field;

• NewArray: construct to create a new (multidimensional) array;

• ArraySlot: construct to access the element of an array;

• ArraySlotUpdate: construct to update the element of an array;

• Tuple: construct to create a new position-indexed tuple;

• NamedTuple: construct to create a new name-indexed tuple;

• TupleProjection: construct to access the component of a tuple;

• TupleUpdate: construct to update the component of a tuple;

• Dummy: temporary place holder in lieu of a name prior to being discriminated into a local or global one.

• Monoid Homomorphism: construct denoting a monoid homomorphism;

• Monoid Comprehesion: construct denoting a monoid comprehension;