无法推断类型参数 'T'。使用 Map.reduce(max) 时

Question

我想从列表中获取最大值。但是自从我迁移到空安全之后，我的代码就不再工作了：

weightChart = [45.3, 21.5, 521.3];
weightChart.reduce(max)

我收到错误：

Couldn't infer type parameter 'T'.  Tried to infer 'double?' for 'T' which doesn't work: Type
 parameter 'T' is declared to extend 'num' producing 'num'. The type 'double?' was inferred from:
 Function type declared as 'T Function<T extends num>(T, T)' used where 'double? Function(double?,
 double?)' is required.  Consider passing explicit type argument(s) to the generic.

Answer 1

我们来试试

import 'dart:math';

void main() {
  List<double> weightChart = [45.3, 21.5, 521.3];
  print(weightChart.reduce(max));
}

无法推断类型参数 'T'。使用 Map.reduce(max) 时

Couldn't infer type parameter 'T'. when using Map.reduce(max)

mapreduce

dart

flutter

dart-null-safety