▁the ▁behaviour ▁of ▁a ▁type - index ed ▁values ▁for ▁a ▁specific ▁constructor ▁using ▁constructor ▁cases , ▁and ▁reuse ▁one ▁generic ▁definition ▁in ▁another ▁using ▁default ▁cases . ▁The ▁resulting ▁type - index ed ▁value ▁can ▁be ▁special ized ▁to ▁any ▁type . ▁Kind - index ed ▁types ▁are ▁types ▁indexed ▁over ▁kinds , ▁defined ▁by ▁giving ▁a ▁case ▁for ▁both ▁* ▁and ▁k ▁→ ▁k '' '. ▁Inst ances ▁are ▁obtained ▁by ▁applying ▁the ▁kind - index ed ▁type ▁to ▁a ▁kind . ▁Gener ic ▁definitions ▁can ▁be ▁used ▁by ▁applying ▁them ▁to ▁a ▁type ▁or ▁kind . ▁This ▁is ▁called ▁generic ▁application . ▁The ▁result ▁is ▁a ▁type ▁or ▁value , ▁depending ▁on ▁which ▁sort ▁of ▁generic ▁definition ▁is ▁applied . Generic ▁abstra ction ▁enables ▁generic ▁definitions ▁be ▁defined ▁by ▁abstract ing ▁a ▁type ▁parameter ▁( of ▁a ▁given ▁kind ). Type - index ed ▁types ▁are ▁types ▁that ▁are ▁indexed ▁over ▁the ▁type ▁construct ors . ▁These ▁can ▁be ▁used ▁to ▁give ▁types ▁to ▁more ▁involved ▁generic ▁values . ▁The ▁resulting ▁type - index ed ▁types ▁can ▁be ▁special ized ▁to ▁any ▁type . ▁ ▁As ▁an ▁example , ▁the ▁equality ▁function ▁in ▁Gener ic ▁H askell : ▁▁▁▁ ▁type ▁Eq ▁{ [ ▁* ▁] } ▁t 1 ▁t 2 ▁= ▁t 1 ▁-> ▁t 2 ▁-> ▁Bool ▁▁▁ ▁type ▁Eq ▁{ [ ▁k ▁-> ▁l ▁] } ▁t 1 ▁t 2 ▁= ▁forall ▁u 1 ▁u 2 . ▁Eq ▁{ [ ▁k ▁] } ▁u 1 ▁u 2 ▁->