Opened 13 years ago
#27 new defect
Eq instance is not compatible with Monoid instance for Picture
| Reported by: | Chris Smith | Owned by: | |
|---|---|---|---|
| Priority: | normal | Milestone: | |
| Component: | Unknown | Version: | 1.5.0 |
| Keywords: | Cc: |
Description
The Monoid instance for Picture obeys neither the identity nor associativity laws when equality is determined by the Eq instance. This could be fixed by either: (a) adding special cases for Blank and Pictures as top-level constructors in the Monoid instance, or (b) flattening the nesting structure implicitly during comparison in the Eq instance.
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