SCALE Sequence(fixed size) implementation

[radkomih]

Array types have fixed size known at compile time, thus the size encoding is omitted.

From the spec:
In some cases, the length indicator is omitted if the length of the sequence is fixed and known by the decoder upfront. Such cases are explicitly stated by the definition of the corresponding type.

Go proposal that might help to make generic parameterized encoding of Array (Sequence with fixed size): golang/go#44253

Related: #4