Specialize collectat for AbstractVector

Author: juliohm

src/utils/basic.jl

@@ -21,7 +21,7 @@ end
 """
     collectat(iter, inds)
 
-Collect iterator `iter` at indices `inds` without materialization.
+Collect iterable `iter` at indices `inds` efficiently.
 """
 function collectat(iter, inds)
   if isempty(inds)
@@ -35,6 +35,8 @@ function collectat(iter, inds)
   end
 end
 
+collectat(vec::AbstractVector, inds) = vec[inds]
+
 """
     XYZ(xyz)