使map-indexed的外部接口与map保持一致。map-indexed现有的用法在实现和接口上都不变。
(map vector (range 10 20) (range 30 35));=>(([10 30] [11 31] [12 32] [13 33] [14 34])) (map-indexed vector (range 10 20) (range 30 35));=>(([0 10 30] [1 11 31] [2 12 32] [3 13 33] [4 14 34]))
补丁:CLJ-1601 map-indexed及测试 8-5-2017.patch - 还增加了对map-indexed的测试
预审:Alex Miller