iterate over a list; `elt` is current list value:
```nu
let planets = [Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune]
$planets | each { |elt| $"($elt) is a planet of the solar system" }
# => ╭───┬─────────────────────────────────────────╮
# => │ 0 │ Mercury is a planet of the solar system │
# => │ 1 │ Venus is a planet of the solar system │
# => │ 2 │ Earth is a planet of the solar system │
# => │ 3 │ Mars is a planet of the solar system │
# => │ 4 │ Jupiter is a planet of the solar system │
# => │ 5 │ Saturn is a planet of the solar system │
# => │ 6 │ Uranus is a planet of the solar system │
# => │ 7 │ Neptune is a planet of the solar system │
# => ╰───┴─────────────────────────────────────────╯
```
iterate over a list with an index and value:
```nu
$planets | enumerate | each { |elt| $"($elt.index + 1) - ($elt.item)" }
# => ╭───┬─────────────╮
# => │ 0 │ 1 - Mercury │
# => │ 1 │ 2 - Venus │
# => │ 2 │ 3 - Earth │
# => │ 3 │ 4 - Mars │
# => │ 4 │ 5 - Jupiter │
# => │ 5 │ 6 - Saturn │
# => │ 6 │ 7 - Uranus │
# => │ 7 │ 8 - Neptune │
# => ╰───┴─────────────╯
```
reduce the list to a single value; `reduce` gives access to accumulator that is applied to each element in the list:
```nu
let scores = [3 8 4]
$"total = ($scores | reduce { |elt, acc| $acc + $elt })"
# => total = 15
```
reduce with an initial value (`--fold`):
```nu
let scores = [3 8 4]
$"total = ($scores | reduce --fold 1 { |elt, acc| $acc * $elt })"
# => total = 96
```
give access to the 3rd item in the list:
```nu
let planets = [Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune]
$planets.2
# => Earth
```
check if any string in the list starts with `E`:
```nu
let planets = [Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune]
$planets | any {|elt| $elt | str starts-with "E" }
# => true
```
slice items that satisfy provided condition:
```nu
let cond = {|x| $x < 0 }; [-1 -2 9 1] | take while $cond
# => ╭───┬────╮
# => │ 0 │ -1 │
# => │ 1 │ -2 │
# => ╰───┴────╯
```
## Tables
sort table:
```nu
ls | sort-by size
```
sort table, get first rows:
```nu
ls | sort-by size | first 5
```
concatenate two tables with same columns:
```nu
let $a = [[first_column second_column third_column]; [foo bar snooze]]
let $b = [[first_column second_column third_column]; [hex seeze feeze]]
$a | append $b
# => ╭───┬──────────────┬───────────────┬──────────────╮
# => │ # │ first_column │ second_column │ third_column │
# => ├───┼──────────────┼───────────────┼──────────────┤
# => │ 0 │ foo │ bar │ snooze │
# => │ 1 │ hex │ seeze │ feeze │
# => ╰───┴──────────────┴───────────────┴──────────────╯
```
remove the last column of a table:
```nu
let teams_scores = [[team score plays]; ['Boston Celtics' 311 3] ['Golden State Warriors', 245 2]]
$teams_scores | drop column
# => ╭───┬───────────────────────┬───────╮
# => │ # │ team │ score │
# => ├───┼───────────────────────┼───────┤
# => │ 0 │ Boston Celtics │ 311 │
# => │ 1 │ Golden State Warriors │ 245 │
# => ╰───┴───────────────────────┴───────╯
```
## Files and Filesystem
open a text file with the default text editor:
```nu
start file.txt
```
save a string to text file:
```nu
'lorem ipsum ' | save file.txt
```
append a string to the end of a text file: