@main[]
$a[^array::create[]]
^first_and_last[Empty hash (^$a[^^hash::create[]]);$a]

$a.1[a]
^first_and_last[One element was added (^$a.1[a]);$a]

^a.delete(1)
^first_and_last[One element was deleted (^^a.delete[1]);$a]

$a.1[a]
^first_and_last[One element was added (^$a.1[a]);$a]

$a[^array::copy[
	$.1[a]
	$.2[b]
	$.3[c]
	$.4[d]
	$.5[e]
]]
^first_and_last[Hash with 5 elements (^$a[ ^$.1[a] ^$.2[b] ^$.3[c] ^$.4[d] ^$.5[e] ]);$a]

^a.delete(5)
^first_and_last[The last element was deleted (^^a.delete[5]);$a]

^a.delete(1)
^first_and_last[The first element was deleted (^^a.delete[1]);$a]

$a.5[e]
^first_and_last[One element was added at the end (^$a.5[e]);$a]

$a.3[cc]
^first_and_last[One element was added at the middle (^$a.3[cc]);$a]

$a[^array::copy[
	$.1[a]
	$.2[b]
	$.3[c]
	$.4[d]
	$.5[e]
]]
^test_at[]
$a[a;b;c;d;e]
^test_at[]

@test_at[]
<h3>_at on array with ^a.count[] elements (^$a[ ^a.foreach[k;v]{^$.${k}[$v]}[ ] ])</h3>
^at(0)
^at(1)
^at(2)
^at(3)
^at(4)

<br />
^at(-1)
^at(-2)
^at(-3)
^at(-4)
^at(-5)

<br />
^at(0)[key]
^at(1)[key]
^at(2)[key]
^at(3)[key]
^at(4)[key]

<br />
^at(0)[value]
^at(1)[value]
^at(2)[value]
^at(3)[value]
^at(4)[value]

<br />
^at(0)[hash]
^at(1)[hash]
^at(2)[hash]
^at(3)[hash]
^at(4)[hash]

^^a._at[first;hash]=^print[^a._at[first;hash]]<br />
^^a._at[last;hash]=^print[^a._at[last;hash]]<br />

<br />
# check if values preserve tainting. keys are always lost tainting
<h3>The first element was replaced (^$a.1[b&b])</h3>
$a.1[b&b]
^^a._at[first;hash]=^print[^a._at[first;hash]]<br />
^at(0)[key]
^at(0)[value]
^at(0)[hash]
<h3>One element was added at the end (^$a.100[^^taint[d&d]])</h3>
$a.100[^taint[d&d]]
^at(5)[key]
^at(5)[value]
^at(5)[hash]
^^a._at[last;hash]=^print[^a._at[last;hash]]<br />

<br />
^do[^^a._at[]]{must fail^a._at[]}
^do[^^a._at[first^;key^;hren]]{must fail^a._at[first;key;hren]}
^do[^^a._at(1){code}]{must fail^a._at(1){code}}
^do[^^a._at(1)(true)]{must fail^a._at(1)(true)}
^do[^^a._at[hren]]{must fail^a._at[hren]}
^do[^^a._at[first][hren]]{must fail^a._at[first][hren]}
^do[^^a._at[last][hren]]{must fail^a._at[last][hren]}
^do[^^a._at(1)[hren]]{must fail^a._at(1)[hren]}

@at[i;type]
^^a._at($i)^if(def $type){[$type]}=^print[^if(def $type){^a._at($i)[$type]}{^a._at($i)}]<br />

@first_and_last[sTitle;a]
^if(def $sTitle){<h3>$sTitle</h3>}
first:last='^a._at[first]':'^a._at[last;value]'<br />
first_key:last_key='^a._at[first;key]':'^a._at[last;key]'<br />

@do[label;code]
$label=^try{${code}}{$exception.handled(true)<b>^taint[as-is;$exception.comment]</b>}<br />

@print[u][k;v]
^if($u is "array" || $u is "hash"){
	$result[^u.foreach[k;v]{'$k':'$v'}[, ]]
}{
	$result[$u]
}