E4146

Type is not supported by range pattern.

MoonBit only support range pattern for integer types. This error occurs when you try to use a type that is not an integer in a range pattern.

错误示例

fn main {
  let value = 1.0
  match value {
    _..<0.0 => println("negative") // Error: Type Double is not supported by range pattern.
    _ => println("zero or positive")
  }
}

建议

For type that is not an integer but implements the Compare trait, you can use multiple if-else expression to achieve the same effect.

fn main {
  let value = 1.0
  if value < 0.0 {
    println("negative")
  } else {
    println("zero or positive")
  }
}