SOURCE_FILE
  FN
    FN_KW "fn"
    WHITESPACE " "
    NAME
      IDENT "foo"
    PARAM_LIST
      L_PAREN "("
      R_PAREN ")"
    WHITESPACE " "
    BLOCK_EXPR
      STMT_LIST
        L_CURLY "{"
        WHITESPACE " "
        LET_STMT
          LET_KW "let"
          WHITESPACE " "
          RECORD_PAT
            PATH
              PATH_SEGMENT
                NAME_REF
                  IDENT "R"
            WHITESPACE " "
            RECORD_PAT_FIELD_LIST
              L_CURLY "{"
              WHITESPACE " "
              RECORD_PAT_FIELD
                NAME_REF
                  IDENT "a"
                COLON ":"
                WHITESPACE " "
                OR_PAT
                  PIPE "|"
                  WHITESPACE " "
                  LITERAL_PAT
                    LITERAL
                      INT_NUMBER "1"
                  WHITESPACE " "
                  PIPE "|"
                  WHITESPACE " "
                  LITERAL_PAT
                    LITERAL
                      INT_NUMBER "2"
              WHITESPACE " "
              R_CURLY "}"
          WHITESPACE " "
          EQ "="
          WHITESPACE " "
          LITERAL
            INT_NUMBER "0"
          SEMICOLON ";"
        WHITESPACE " "
        R_CURLY "}"
  WHITESPACE "\n"
