
Robbert Krebbers authored
This provides significant robustness against looping type class search. As a consequence, at many places throughout the library we had to add additional typing information to lemmas. This was to be expected, since most of the old lemmas were ambiguous. For example: Section fin_collection. Context `{FinCollection A C}. size_singleton (x : A) : size {[ x ]} = 1. In this case, the lemma does not tell us which `FinCollection` with elements `A` we are talking about. So, `{[ x ]}` could not only refer to the singleton operation of the `FinCollection A C` in the section, but also to any other `FinCollection` in the development. To make this lemma unambigious, it should be written as: Lemma size_singleton (x : A) : size ({[ x ]} : C) = 1. In similar spirit, lemmas like the one below were also ambiguous: Lemma lookup_alter_None {A} (f : A → A) m i j : alter f i m !! j = None
↔ m !! j = None. It is not clear which finite map implementation we are talking about. To make this lemma unambigious, it should be written as: Lemma lookup_alter_None {A} (f : A → A) (m : M A) i j : alter f i m !! j = None↔ m !! j = None. That is, we have to specify the type of `m`.7d7c9871