I vaguely recall seeing a mailing list thread where `{-}` was proposed. I think ...

yen223 · on March 16, 2013

Wouldn't it lead to the same problem of a lack of consistency?

    dict: {} 
    list: []
    tuple: ()
    set: {-}

philipbjorge · on March 16, 2013

I originally implemented it that way and had that exact same issue (it's one of the revisions on github). Similarly, {/} would also be a problem.

digisign · on March 16, 2013

How about {,} or s{} ?

mkhattab · on March 16, 2013

I think {,} is intuitive because it reminds me of syntax for one-element tuples, e.g. (1,) -- but it may make code harder to read, which is not Pythonic.

philipbjorge · on March 16, 2013

I didn't think to do {,} which I like. s{} looks weird to me, but I couldn't tell you why.

digisign · on March 16, 2013

The s{} alternatve is based on the strange r'' or u'' syntax i've gotten used to.