allow constants for string literals types

[zpdDG4gta8XKpMCd]

const vow = 'will never change';
let promise: vow;

[RyanCavanaugh]

We can't do this since it would be a breaking change -- vow has not previously introduced an entry in the type namespace, so doing so now would mean random types would start getting shadowed.

typeof vow should do what you want here (if we made consts be of their string literal type @DanielRosenwasser please confirm?).

[zpdDG4gta8XKpMCd]

typeof vow should do what you want here

in the expression context typeof vow gets me "string"
in the type expression context it gets me "will never change", but it's a string literal type which I cannot assign to a variable

... if we made consts be of their string literal type

if we assuming it's hasn't yet been done, then it answers it

[DanielRosenwasser]

Like @RyanCavanaugh said, in order to do typeof vow, you'd need #5796. That said, I don't know if that PR will go in. The behavior isn't entirely ideal because it's not clear when you want the literal type and not string.

[mhegazy]

Here is the proposal: #6167 (comment)

[sceutre]

What about allowing interpolated strings as string literal types. So:

const vow = "will never change";
let promise: `${vow}`;

[mhegazy]

The issue in the OP should be fixed by #10676

Allowing string interpolation, or any form of string manipulation in type positions is not something we are looking to allow.

for this specific example, use typeof operator, e.g. let promise: typeof vow; and this should be "will never change".

[mhegazy]

@Aleksey-Bykov do you agree this proposal is covered by #10676 and typeof?