问Powershell -Unique转换为ae

EN

$Test = @('æ','ae')
$Test | Select-Object -Unique
# æ

PS> Get-Culture

LCID             Name             DisplayName
----             ----             -----------
2057             en-GB            English (United Kingdom)

PS> $data = @( "ae", "æ" )
PS> [System.Linq.Enumerable]::Distinct([string[]]$data, [System.StringComparer]::Ordinal )
ae
æ

class FirstLetterComparer : System.Collections.Generic.IEqualityComparer[string] {
  [bool]Equals([string]$x, [string]$y) { return $x[0] -eq $y[0]; }
  [int]GetHashCode([string] $x) { return $x[0].GetHashCode(); }
}

# returns the first item in the list that starts with each distinct character.
# note that "abb" is omitted because it starts with the same first letter as "aaa"
# so it's not "first letter distinct".
$data = @( "aaa", "abb", "bbb" )
[System.Linq.Enumerable]::Distinct([string[]]$data, [FirstLetterComparer]::new() )
# aaa
# bbb

- _Windows PowerShell_, the legacy, ships-with-Windows edition, whose latest and final version is 5.1, which builds on the legacy, Windows-only _.NET Framework_, which uses [**NSL (National Language Support)**](https://learn.microsoft.com/en-us/windows/win32/intl/national-language-support) for culture-specific information.

- [_PowerShell (Core) 7+_](https://github.com/PowerShell/PowerShell/blob/master/README.md), which builds on the cross-platform _.NET 5+_ edition, which now uses the [**ICU (International Components for Unicode) library**](https://icu.unicode.org/) _by default_ - though [_on Windows_ you can opt-into still using NLS](https://learn.microsoft.com/en-us/dotnet/core/extensions/globalization-icu).

- The **ligature** **`æ`** **is considered** _**equivalent**_ **to the sequence of its** _**constituent letters**_ **in** _**most**_ **cultures**, _**except**_ in those:

    - where `æ` is in use as a character in its own right ...
    - _and_ is _not_ considered equivalent to the sequence of its constituent letters.

- These exceptions are (only the so-called _neutral_ (non-nation-specific) cultures are listed, not also their national varieties):

    - da (Danish)
    - is (Icelandic)
    - kl (Kalaallisut)
    - nb (Norwegian Bokmål)
    - nn (Norwegian Nynorsk)
    - no (Norwegian)
    - se (Northern Sami)
    - sma (Sami (Southern))
    - smj (Sami (Lule))
    - smn (Sami (Inari))
    - sms (Sami (Skolt))

- **Other ligatures have multi-letter equivalents in** _**all**_ **cultures**, such as [`œ`](https://en.wikipedia.org/wiki/%C5%92) vs. `oe`; there are also ligatures whose multi-letter equivalent is _not_ the sequence of its constituent letters, but a modern equivalent, e.g., German [`ß`](https://en.wikipedia.org/wiki/%C3%9F) (which originated from `sz`) is considered equivalent to `ss`.

- At least as of the ICU version that underlies PowerShell 7.2.4, **ligatures** _**in general**_ **are seemingly** _**never**_ **considered equivalent to their constituent letters** in string comparisons.