Should you be able to initialize a float with a char?

[kdevel]

On Thursday, 19 May 2022 at 20:48:47 UTC, Ali Çehreli wrote:
[...]
> > "However, the assumption that setting bit 5 of the
> representation will
> > convert uppercase letters to lowercase is not valid for
> EBCDIC." [1]
> >
> > [1] Does C and C++ guarantee the ASCII of [a-f] and [A-F]
> characters?
> >      https://ogeek.cn/qa/?qa=669486/
>
> In D, char is UTF-8 and ASCII is a subset of UTF-8.

The latter part, that ASCII is a subset of UTF-8, is 1†. I 
disagree with the wording of the former part, that in D a char 
"is" UTF-8.

> Walter's code above is valid without making any ASCII 
> assumption.

Walter made the 0 claim "It does not assume it, it tests for if 
it would be valid [ascii and not unicode]" [2] ‡

Okay. Let's do UTF-8:

```
import std.stdio;
import std.string;
import std.utf;

char char_tolower_bright (char c)
{
    if ('A' <= c && c <= 'Z')
       c = c | 0x20;
    return c;
}

string tolower_bright (string s)
{
    string t;
    foreach (c; s.byCodeUnit)
       t ~= c.char_tolower_bright;
    return t;
}

void process_strings (string s)
{
    writefln!"input            : %s" (s);
    auto t = s.tolower_bright;
    writefln!"bright           : %s" (t);
    auto u = s.toLower;
    writefln!"toLower (std.utf): %s" (u);
}

void main ()
{
    process_strings ("A Ä");
    process_strings ("A Ä");
}
```

Free of charge I compiled and ran this for you:

    $ dmd lcb
    $ ./lcb
    input            : A Ä
    bright           : a Ä
    toLower (std.utf): a ä
    input            : A Ä
    bright           : a ä
    toLower (std.utf): a ä

See the problem?

   † Hint for interpretation: booleans "are" integers.
[2] http://forum.dlang.org/post/t662ll$tnm$1@digitalmars.com
   ‡ There is probably no consensus about what "it" means.