| | Some definitions of interest. |
|
| l_before | Def x before y  l == [x; y]  l |
| | | Thm*  T:Type, l:T List, x,y:T. x before y l Prop |
|
| int_seg | Def {i..j } == {k: | i  k < j } |
| | | Thm* m,n:. {m..n} Type |
|
| length | Def ||as|| == Case of as; nil  0 ; a.as' ||as'||+1 (recursive) |
| | | Thm* A:Type, l:A List. ||l|| |
| | | Thm* ||nil|| |
|
| map | Def map(f;as) == Case of as; nil nil ; a.as' [(f(a)) / map(f;as')] (recursive) |
| | | Thm* A,B:Type, f:(A  B), l:A List. map(f;l) B List |
| | | Thm* A,B:Type, f:(AB), l:A List . map(f;l) B List |
|
| select | Def l[i] == hd(nth_tl(i;l)) |
| | | Thm* A:Type, l:A List, n:. 0n   n < ||l|| l[n] A |
