13. The system of claim 7 , wherein a code element comprises one of: a function, a class, an object, a variable, an expression, a script, a global, a primitive, a module, an interface, an enumerated list, an array, an alias for a type, a parameter, a property, a type, a method, a function expression, a call signature, an index signature, an object type, or a function type.
7. A system comprising: at least one processor: a memory connected to the at least one processor; and at least one module that when loaded into the memory causes the at least one processor to: detect a change in program source code during an interactive editing session when the change changes a data type associated with a first code element, the change affecting a data type associated with a second code element; delay computation of an effect of the change in the data type associated with the first code element on the second code element until a request for the data type of the second code element is received; and in response to detecting a request for information associated with the data type of the second code element, display information on how the data type of the second code element was determined.