f# - Attributes and let statements in type members -

i using fsunit write unit tests in f# , have noticed odd behaviour around attributes , let statements in type members , wondering if explain it?

if write test this:

[<fact>] member test.   ``test works correctly`` () =      let x = 1      x + 2 |> should equal 3 

i error in visual studio 2012 on first character of 'x + 2' line saying:

unexpected keyword 'let' or 'use' in expression. expected 'in' or other token.

using 'let ... in' gets around error, although if want use more 1 let gets messy quickly:

[<fact>] member test.   ``test works correctly`` () =     let x = 1     in x + 2 |> should equal 3 

i discovered having attribute on separate line gets around error:

[<fact>] member test.   ``test works correctly`` () =      let x = 1      x + 2 |> should equal 3 

can provide insight on why first code snippet causes error other 2 not?

in first snippet, had 2 indentation errors. first issue ''test works correctly'' should indented after member keyword. second 1 body of function should indented after lines of member definitions.

if fix first error:

[<fact>] member test.            ``test works correctly`` () =     let x = 1     x + 2 |> should equal 3 

the compiler issue "possible incorrect indentation" warning, can fix indenting body of function further:

[<fact>] member test.            ``test works correctly`` () =              let x = 1              x + 2 |> should equal 3 

in second snippet, use of in keyword triggers verbose syntax indentation doesn't matter anymore. in last example, member happens have lowest indentation; incidentally have correct indentation.

that said, should avoid break member definitions multiple lines. in of cases, can use let bindings instead of more verbose member bindings.

[<fact>] let ``test works correctly``() =     let x = 1     x + 2 |> should equal 3