; Some functions about trees
[defun tree/zip [keys values]
"Return a tree where KEYS point to VALUES"
[def ret [tree/new]]
[while keys
[tree/set! ret [car keys] [car values]]
[cdr! keys]
[cdr! values]
]
ret
]
[defun tree/++ [t k]
"Increment value at K in T by 1"
[tree/set! t k [+ 1 [int [tree/get t k]]]]
]
