Record functions

Read and combine record fields.

Function	Description
[keys(r: record) → [utf8]](functionfnkeys)	The field names of a record, in deterministic (sorted) order.
map_values(r: record, f: fn (T) -> U) → record	Apply a function to every field value of a record, keeping the keys.
merge(a: record, b: record) → record	Combine two records into one; fields of b win on a name clash.
[values(r: record) → [T]](functionfnvalues)	The field values of a record, in the same order as keys.