Improved type error reporting

. The error reports produced by compilers for languages with polymorphic type inference are often uninformative. Several attempts have been made to produce improved error reports. We dene a manifesto for good error reports and use it to evaluate both the traditional algorithms, and several improved algorithms, including two of our own devising. 1 Introduction Debugging type errors in programs written in polymorphic languages with type inference is hard [13, 7]. One reason is that much...