Opened 12 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:


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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