reduce<Type> function

Type reduce<Type>(Iterable<Type> input)

Reduces a list of objects to a single object by concatenating them.

E.g.:

• A list of strings will be concatenated.
• A list of chat messages will be concatenated into a single chat message.
• A list of language model results will be concatenated into a single language model result.
• A list of documents will be concatenated into a single document.
• A list of lists will be reduced to a single list containing a single reduced item.
• A list of maps will be reduced to a single map containing the reduced items.
• If a type is not recognized, the last item in the list will be returned.

Implementation

Type reduce<Type>(final Iterable<Type> input) {
  if (input.isEmpty) {
    throw Exception('Cannot reduce an empty list');
  } else if (input.length == 1) {
    return input.first;
  }

  final first = input.first;
  return switch (first) {
    String() => input.cast<String>().join(),
    ChatMessage() =>
      input.cast<ChatMessage>().reduce((final a, final b) => a.concat(b)),
    PromptValue() =>
      input.cast<PromptValue>().reduce((final a, final b) => a.concat(b)),
    LanguageModelResult() => input
        .cast<LanguageModelResult>()
        .reduce((final a, final b) => a.concat(b)),
    Document() =>
      input.cast<Document>().reduce((final a, final b) => a.concat(b)),
    Iterable<String>() => _reduceIterable(input.cast<Iterable<String>>()),
    Iterable<Object>() => _reduceIterable(input.cast<Iterable<Object>>()),
    Iterable<dynamic>() => _reduceIterable(input.cast<Iterable<dynamic>>()),
    Map<String, String>() => _reduceMap(input.cast<Map<String, String>>()),
    Map<String, Object>() => _reduceMap(input.cast<Map<String, Object>>()),
    Map<String, dynamic>() => _reduceMap(input.cast<Map<String, dynamic>>()),
    Map<dynamic, dynamic>() => _reduceMap(input.cast<Map<dynamic, dynamic>>()),
    _ => input.last,
  } as Type;
}