f# - 轻量级语法和嵌套记录

Question

这个程序:

type A = { a : int }
type B = { b : A }

//34567890
let r = {
  b = {      // line 6
    a = 2    // line 7 
  } 
}

在 mono/fsharpc 下产生此警告两次:

/Users/debois/git/dcr/foo.fs(7,5): warning FS0058: Possible incorrect indentation: this token is offside of context started at position (6:7). Try indenting this token further or using standard formatting conventions.

为什么会出现这个警告？ f#-spec p. 228让我觉得'{'后面的标记'a'设置了一个新的越位线，在这种情况下应该没有问题？

为什么会出现两次？

谢谢，

索伦

完整输出:

dcr > fsharpc foo.fs
F# Compiler for F# 3.0 (Open Source Edition)
Freely distributed under the Apache 2.0 Open Source License

/Users/debois/git/dcr/foo.fs(7,5): warning FS0058: Possible incorrect indentation: this token is offside of context started at position (6:7). Try indenting this token further or using standard formatting conventions.

/Users/debois/git/dcr/foo.fs(7,5): warning FS0058: Possible incorrect indentation: this token is offside of context started at position (6:7). Try indenting this token further or using standard formatting conventions.
dcr > 

Answer 1

将您的代码重新格式化为

type A = { a : int }
type B = { b : A }

//34567890
let r = { b = { a = 2 } }

或者

let r =
    {
       b = { a = 2 } 
    }

即 { 是最左边的标记。

编辑:一个场外行以 { 开头，因此您需要至少缩进与 { 一样多的缩进，换行之后不是强制性的。而第二个警告也是出于同样的原因。