Field descriptor type. A schema contains a map of indexes to values of this type, which indicate whether the field is required or optional, along with a description of the type of the field value and a scanner for values of that type.

The type of a schema

Use schema fields to make a record schema for scanning records according to fields. If ~ignore:(n, p) is provided, then as many as n unrecognized fields are scanned according to p and their values are discarded.

Use range schema to get the minimum and maximum number of fields that can be processed by scanning with schema.

The type of a packed record produced by scanning with a schema.

Use scan schema to scan a record according to schema producing a pack value containing all the values in the record.

Use unpack pack index nym to unpack from pack the value for the field named by index with the type nym.

Note well: fields with Optional type in the schema are packed with the corresponding Cf_type.Option type nym, and the unpacked value is either Some v if the field is present in the scanned record, or None if the field was not present.