These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 0.96 s (backtrack: 0/20).

[ebuild  N     ] dev-lang/mlton-20180207:0/20180207::gentoo  USE="-binary -bootstrap-smlnj -doc -pax-kernel -stage3" 42751 KiB

Total: 1 package (1 new), Size of downloads: 42751 KiB