Looks like they don't acknowledge it on the landing page, but this is probably an implementation of Haskell, or of a dialect of Haskell.
Unfortunately, the "(that happens to be Haskell)" part is completely left out on the entry page. This gives a terrible first impression, because it seems like if someone would be trying to bootleg those 26 years that went into Haskell and sell them of as their own achievement. The documentation does a reasonable effort to set this straight, but the aftertaste from the first impression remains.