Yeah, I saw that it uses mueval, but it's still conceivable that TryHaskell itself could hack support for let on top of it. Apparently Chris planned to do it [1].
Note that in "let t=bar in foo" the scope of t is restricted to foo, so the example above still doesn't work.
Note that in "let t=bar in foo" the scope of t is restricted to foo, so the example above still doesn't work.
[1] http://www.reddit.com/r/haskell/comments/b58rk/try_haskell/c... ([deleted] = Chris Doner)