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|
(local {: insert} (require :toast.table))
(fn dec [n]
"Decrement n by 1."
(- n 1))
(fn inc [n]
"Increment n by 1."
(+ n 1))
(fn drop [n xs]
"Returns a table of all but the first n elements in xs."
(let [out []]
(each [i v (ipairs xs)]
(when (> i n) (insert out v)))
out))
(fn first [xs]
"The first element in a sequential table."
(. xs 1))
(fn last [xs]
"The last element in a sequential table."
(. xs (length xs)))
(fn group [n xs]
"Group elements in xs in groups of n.
Extra elements at the end will sit in the final group.
For example, (group 2 [1 2 3 4 5]) results in [[1 2] [3 4] [5]]."
(let [ll #(length (last $))
donext #(= (ll $) n)]
(accumulate [out [[]]
_ v (ipairs xs)]
(do (when (donext out)
(insert out []))
(insert (last out) v)
out))))
(fn map [f xs]
"Returns a sequential table consisting of the result of apply f to every item in xs."
(accumulate [out []
_ v (ipairs xs)]
(let [mapped (f v)]
(insert out (if (= 0 (select :# mapped))
nil
mapped)))))
{: dec
: inc
: drop
: group
: first
: last}
|
