Compilers Course 2016, Cambridge CL

My improvements

• Fixed the while loop implementations in slang_v2 for compilers 2 through 4.
  The value from the body (always ()) was being left on the stack, unneccesarily using space. In most of the interpreters, this also meant a crash when it exited the loop and tried to apply the remaining code to a stack of ()s

• Changed (*…*) comments to work over new lines.
  Previously they could be opened and closed on the same line, but new-lines would also close them, so they were effectively single-line comments

• Added pattern matching for the arguments of functions and lambdas, including allowing let f() = ... which wasn't possible before. Patterns can be nested, so deconstructing nested pairs works too.

• Added pattern matching to let expressions to allow the deconstruction of pairs

• Added pattern matching to case expressions to allow deconstruction of pairs within unions

• Removed the need for the end keyword after if expressions, while loops, lambdas, let … in expressions, and case expressions