-- Data builtins: sum, avg, flat, grp, rgx.
-- Aggregation and reshape for data pipelines.
-- Sum a list of numbers
total xs:L n>n;sum xs
-- Average a list of numbers
mean xs:L n>n;avg xs
-- Flatten nested lists one level
smoosh>L n;flat [[1, 2], [3], [4, 5]]
-- Group numbers into "big" (>5) and "small" by key function
cl x:n>t;>x 5{"big"}{"small"}
classify xs:L n>M t L n;grp cl xs
-- Extract all numbers from a string with regex
nums s:t>L t;rgx "\d+" s
-- engine-skip: vm
-- run: total [1,2,3,4,5]
-- out: 15
-- run: mean [2,4,6]
-- out: 4
-- run: smoosh
-- out: [1, 2, 3, 4, 5]
-- run: nums abc123def456
-- out: [123, 456]