data ==== Various data types. Basic types: * [empty](empty.lean) : the empty type * [unit](unit.lean) : the singleton type * [bool](bool.lean) : the boolean values * [num](num.lean) : generic numerals * [string](string.lean) : ascii strings * [nat](nat/nat.md) : the natural numbers * [fin](fin.lean) : finite ordinals * [int](int/int.md) : the integers Constructors: * [prod](prod.lean) : cartesian product * [sum](sum.lean) * [sigma](sigma.lean) : the dependent product * [option](option.lean) * [subtype](subtype.lean) * [quotient](quotient/quotient.md) * [list](list/list.md) * [set](set.lean) * [vector](vector.lean)