Subtraction of two chars

[Happypig375]

Subtraction of two chars

F# has addition of two chars.

let z = 'a' + '\025'
let Z = 'A' + '\025'

I propose we also add subtraction of two chars.

let a = 'z' - '\025'
let A = 'Z' - \025'

The existing way of approaching this problem in F# is

let (--) a b = int a - int b |> char
let a = 'z' -- '\025'
let A = 'Z' -- '\025'

Pros and Cons

The advantages of making this adjustment to F# are

1. Consistency
2. Convenience
3. Conciseness

The disadvantage of making this adjustment to F# is that this treats chars more like ints which may confuse beginners. However, addition is already present. It's inconsistent to not have subtraction.

Extra information

Estimated cost (XS, S, M, L, XL, XXL): XS - Just add the overload

Related suggestions: None

Affidavit (please submit!)

Please tick this by placing a cross in the box:

• This is not a question (e.g. like one you might ask on stackoverflow) and I have searched stackoverflow for discussions of this issue
• I have searched both open and closed suggestions on this site and believe this is not a duplicate
• This is not something which has obviously "already been decided" in previous versions of F#. If you're questioning a fundamental design decision that has obviously already been taken (e.g. "Make F# untyped") then please don't submit it.

Please tick all that apply:

• This is not a breaking change to the F# language design
• I or my company would be willing to help implement and/or test this

For Readers

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[dsyme]

Hmmmm.... This isn't approved yet - and does come under the "already decided in F# 1.0" category. This was rejected in F# 1.0 because, well, subtracting arbitrary unicode characters does seem wrong, pointless, even if there are some use-cases in the ASCII range.

That said, I'd like other opinions on this. The 5 thumbs-up seem to indicate that people have no significant concerns.

[Happypig375]

It's not only for the ASCII range, but also for conversion between half-width and full-width forms, conversions to enclosed alphanumerics, etc.

[dsyme]

It's not only for the ASCII range, but also for conversion between half-width and full-width forms, conversions to enclosed alphanumerics, etc.

I see. OK, then yes, we can do this

[edgarfgp]

This can be closed as it has been completed here dotnet/fsharp#11681 by @Happypig375