In julia, f!(types)(parameter) means that f! is a mutating function acting on types which returns a closure which is then called on parameter.

We just write Type{paramemer}

It seems odd to say "we just write" for some arbitrary choice with its own tradeoffs; {} mean a set in Python or a literal array initialiser in C# or a scriptblock in PowerShell or a dfn in Dyalog APL or a JSON dictionary, etc. With only a limited set of whatever symbols happened to end up on a US ASCII keyboard 40+ years ago, there is heavy competition for them, it's why J broke the symmetry of pairs and went for two-character symbols, why PowerShell went for comparators like -gt and -lt, why C# has => which is completely different from <=, why << is not a double application of less-than but is bit shifting ...

To act like there's an objectively better use for {} is to miss how many tradeoffs there are, and how many things people want symbols for out of a standard keyboard.

My point was just that we find Type{parameter} to be nice pleasing syntax, and so reserved the curly braces for that.

Of course it’s not objectively better, that’s a dumb attitude towards syntax.