When I read Julia source codes, sometimes the type parameterization writes `where T`

, sometimes `where {T}`

. Are they different or the same?

They are the same. `where {T1, T2, T3}`

is the same as `where T3 where T2 where T1`

is the same as `where {T3} where {T2} where {T1}`

.

Some people, me included, prefer to always put in the brackets even if unneeded, in order to aid the eye at scanning for type parameters. But that is a matter of taste. There probably is some piece of history here that I donâ€™t know.

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not much history beyond the â€śdiscoveryâ€ť that writing

`where {T1, T2, T3}`

leads to nicer visuals than `where T3 where T2 where T1`

there are occasions when the long form is helpful, where one or more of the Ti are compound or triangular locally