Mercurial > urweb
comparison lib/ur/list.ur @ 1345:9e0fa4f6ac93
Fiddly tweaks
| author | Adam Chlipala <adam@chlipala.net> |
|---|---|
| date | Thu, 16 Dec 2010 13:35:40 -0500 |
| parents | 80bff6449f41 |
| children | d328983dc5a6 |
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| 1344:660a2715e2bd | 1345:9e0fa4f6ac93 |
|---|---|
| 320 nth ls' (n-1) | 320 nth ls' (n-1) |
| 321 in | 321 in |
| 322 nth | 322 nth |
| 323 end | 323 end |
| 324 | 324 |
| 325 fun replaceNth [a] (ls : list a) (n : int) (v : a) : list a = | |
| 326 let | |
| 327 fun repNth (ls : list a) (n : int) (acc : list a) = | |
| 328 case ls of | |
| 329 [] => rev acc | |
| 330 | x :: ls' => if n <= 0 then | |
| 331 revAppend acc (v :: ls') | |
| 332 else | |
| 333 repNth ls' (n-1) (x :: acc) | |
| 334 in | |
| 335 repNth ls n [] | |
| 336 end | |
| 337 | |
| 325 fun assoc [a] [b] (_ : eq a) (x : a) = | 338 fun assoc [a] [b] (_ : eq a) (x : a) = |
| 326 let | 339 let |
| 327 fun assoc' (ls : list (a * b)) = | 340 fun assoc' (ls : list (a * b)) = |
| 328 case ls of | 341 case ls of |
| 329 [] => None | 342 [] => None |