Yaml version of EricP's json https://twitter.com/bblfish/status/1533823391148425216

EricP.example.yaml

# <-- S is a fresh BNode (or steal @id conventions from JSON-LD)
type: record               # <-- emit { S rdf:type <record> .} (outer-most frame only)
namespace: example.avro    # <- no effect; used for avro resultion
name: array_union          # <- no effect (i don't even know what this is for)
fields:                    # <-- implies a list of nested statements with subject S
- name: study i            # <-- V for a complex type is a fresh BNode
  "@id": http:...name      # <-- emit { S <http:...study> V . }
  type:                    # <-- S := V
    name: study            # <- no effect
    type: record           # <-- no effect
    fields:                # <-- implies a list of nested statements with subject V
    - name: name           # <-- validates a value V
      type: string         # <-- with DT := xsd:string
      "@id": http:...name  # <-- emit { S <http:...name> V^^DT . }
    - name: corpus         # <-- V is a fresh BNode
      "@id": http:...corpus # <-- P := 
      type:
      - null               # <-- No triple emitted if null (at least, that was the DirectMapping choice)
      - type: array        # <-- in a type 'array', so keep track of tail of list: TAIL := { 
                           #                  S <http:...corpus>  @TBD . }'
        name: corpus_name_0
        items:             # <-- for each item
          name: _name_0    # <-- no effect
          type: record     # <-- LI := fresh BNode;
                           # emit TAIL with LI substituted in for @TBD
                           # emit { LI rdf:first foaf:name S };
                           # TAIL := { LI rdf:rest @TBD . }
          fields:          # <-- S is a fresh BNode
          - name: name     # <-- validates a value V
            type: string   # <-- with DT := xsd:string
            "@id": foaf:name # <-- emit { S foaf:name V^^DT };
          - name: status   # <-- validates a value V
            "@id": http:...status
            type:
              name: StatusType
              type: enum   # <-- with termType := iri
              symbols:
              - enrolled   # <-- if matched, emit { S <http:...status> <enrolled> . }
              - initiated  # <-- if matched, emit { S <http:...status> <initiated> . }
              - completed  # <-- if matched, emit { S <http:...status> <completed> . }
                           # at end of items, emit TAIL with rdf:nill substituted in for @TBD.'