input: '{"abc": 1, "abcd": 2, "Foo": 3}'
output: ['["Foo", "abc", "abcd"]']
+ - title: `select`
+ body: |
+
+ The function `select(foo)` produces its input unchanged if
+ `foo` returns true for that input, and produces no output
+ otherwise.
+
+ It's useful for filtering lists: `[1,2,3] | select(. >= 2)`
+ will give you `[3]`.
+
+ examples:
+ - program: 'select(. >= 2)'
+ input: '[1,5,3,0,7]'
+ output: ['[5,3,7]']
+
+ - title: `empty`
+ body: |
+
+ `empty` returns no results. None at all. Not even `null`.
+
+ It's useful on occasion. You'll know if you need it :)
+
+ examples:
+ - program: '1, empty, 2'
+ input: 'null'
+ output: [1,2]
+ - program: '[1,2,empty,3]'
+ input: 'null'
+ output: ['[1,2,3]']
+
- title: `map(x)`
body: |