The Case constraint is used for functions like bool, case_, maybeTable, nullable, all of which ultimately compile down to a PostgreSQL CASE statement. Case has two instances: an overlapping Table Expr a => Case a instance, and a Case b => Case (a -> b) instance, that allows expressions like maybeTable id (+) which would not have been possible for.
The
Caseconstraint is used for functions likebool,case_,maybeTable,nullable, all of which ultimately compile down to a PostgreSQLCASEstatement.Casehas two instances: an overlappingTable Expr a => Case ainstance, and aCase b => Case (a -> b)instance, that allows expressions likemaybeTable id (+)which would not have been possible for.