use lazy generators

Author: rafaqz

src/terms.jl

@@ -538,12 +538,12 @@ modelcols(t::InterceptTerm{false}, d) = Matrix{Float64}(undef, size(first(d),1),
 modelcols(t::FormulaTerm, d::NamedTuple) = (modelcols(t.lhs,d), modelcols(t.rhs, d))
 
 function modelcols(t::MatrixTerm, d::ColumnTable)
-    mat = reduce(hcat, [modelcols(tt, d) for tt in t.terms])
+    mat = reduce(hcat, (modelcols(tt, d) for tt in t.terms))
     reshape(mat, size(mat, 1), :)
 end
 
 modelcols(t::MatrixTerm, d::NamedTuple) =
-    reduce(vcat, [modelcols(tt, d) for tt in t.terms])
+    reduce(vcat, (modelcols(tt, d) for tt in t.terms))
 
 vectorize(x::Tuple) = collect(x)
 vectorize(x::AbstractVector) = x