|Version 4 (modified by ross@…, 8 years ago) (diff)|
Allow Undecidable Instances
There are no restrictions on the form of instance declarations (see FlexibleInstances). As a result, context reduction need not terminate, so implementations impose some limit on the depth of inference.
- Undecidable instances in the GHC User's guide.
- offered by GHC and Hugs with appropriate options
- no clear boundary