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9 type Path = List[Pos] // a path...a list of positions |
9 type Path = List[Pos] // a path...a list of positions |
10 |
10 |
11 |
11 |
12 //(2a) Implement a first-function that finds the first |
12 //(2a) Implement a first-function that finds the first |
13 // element, say x, in the list xs where f is not None. |
13 // element, say x, in the list xs where f is not None. |
14 // In that case return f(x), otherwise None. If possible, |
14 // In that case Return f(x), otherwise None. If possible, |
15 // calculate f(x) only once. |
15 // calculate f(x) only once. |
16 |
16 |
17 //def first(xs: List[Pos], f: Pos => Option[Path]) : Option[Path] = ... |
17 //def first(xs: List[Pos], f: Pos => Option[Path]) : Option[Path] = ... |
18 |
18 |
19 //(2b) Implement a function that uses the first-function for |
19 //(2b) Implement a function that uses the first-function for |