1	#!/usr/bin/env bash
2	#
3	# Arrays decay upon assignment (without splicing) and equality. This will not
4	# be true in Oil -- arrays will be first class.
5
6	#### Assignment Causes Array Decay
7	set -- x y z
8	argv.py "[$@]"
9	var="[$@]"
10	argv.py "$var"
11	## STDOUT:
12	['[x', 'y', 'z]']
13	['[x y z]']
14	## END
15
16	#### Array Decay with IFS
17	IFS=x
18	set -- x y z
19	var="[$@]"
20	argv.py "$var"
21	## stdout: ['[x y z]']
22
23	#### User arrays decay
24	declare -a a b
25	a=(x y z)
26	b="${a[@]}" # this collapses to a string
27	c=("${a[@]}") # this preserves the array
28	c[1]=YYY # mutate a copy -- doesn't affect the original
29	argv.py "${a[@]}"
30	argv.py "${b}"
31	argv.py "${c[@]}"
32	## STDOUT:
33	['x', 'y', 'z']
34	['x y z']
35	['x', 'YYY', 'z']
36	## END
37
38	#### $array is not valid in OSH, is ${array[0]} in ksh/bash
39	a=(1 '2 3')
40	echo $a
41	## STDOUT:
42	1
43	## END
44	## OK osh status: 1
45	## OK osh stdout-json: ""
46
47	#### ${array} is not valid in OSH, is ${array[0]} in ksh/bash
48	a=(1 '2 3')
49	echo ${a}
50	## STDOUT:
51	1
52	## END
53	## OK osh status: 1
54	## OK osh stdout-json: ""
55
56	#### Assign to array index without initialization
57	a[5]=5
58	a[6]=6
59	echo "${a[@]}" ${#a[@]}
60	## stdout: 5 6 2
61
62	#### a[40] grows array
63	a=(1 2 3)
64	a[1]=5
65	a[40]=30 # out of order
66	a[10]=20
67	echo "${a[@]}" "${#a[@]}" # length is 1
68	## stdout: 1 5 3 20 30 5
69
70	#### array decays to string when comparing with [[ a = b ]]
71	a=('1 2' '3 4')
72	s='1 2 3 4' # length 2, length 4
73	echo ${#a[@]} ${#s}
74	[[ "${a[@]}" = "$s" ]] && echo EQUAL
75	## STDOUT:
76	2 7
77	EQUAL
78	## END
79
80	#### ++ on a whole array increments the first element (disallowed in OSH)
81	a=(1 10)
82	(( a++ )) # doesn't make sense
83	echo "${a[@]}"
84	## stdout: 2 10
85	## OK osh status: 1
86	## OK osh stdout-json: ""
87
88	#### Apply vectorized operations on ${a[*]}
89	a=('-x-' 'y-y' '-z-')
90
91	# This does the prefix stripping FIRST, and then it joins.
92	argv.py "${a[*]#-}"
93	## STDOUT:
94	['x- y-y z-']
95	## END
96	## N-I mksh status: 1
97	## N-I mksh stdout-json: ""