blob: 3c77e4abcc6f2ff472606034a48f442905a08e78 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
|
(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 empty? [xs]
"Returns true if the lengthable contains no elements."
(= 0 (length xs)))
(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]].
One exception is if xs is empty, in which case an empty collection is returned."
(if (empty? xs)
[]
(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
: empty?
: group
: first
: last}
|
