analyzer: refactor value type of neededPackages map

[alexandear]

The boolean value of the neededPackages[fname] map is never used, so we can change it to struct{}.

[catenacyber]

Why does this matter ?
I find bool more readable than struct even if I miss a good golang set to use instead of this kind of map

[ccoVeille]

It's about memory allocation. map[whatever]struct{} are known to be memory efficient, but also to be used for deduplication of keys of the map.

Right now with slices and map packages. I don't see them much

[catenacyber]

It's about memory allocation. map[whatever]struct{} are known to be memory efficient

TIL

but also to be used for deduplication of keys of the map.

How so ?

[ccoVeille]

but also to be used for deduplication of keys of the map.

How so ?

Like a for loop

known := make(maps[string]struct{})
for _, v := range []string{"aa", "bb", "aa"} {
    if _, found := known[v]; found {
        continue
    }
    known[v] = struct{}{}

    // do something, like a log, reading a file
}

But now you have methods like slices.Sort + slices.Compacts

They can be used with maps.Keys or maps.Values