It's funny you posted this, because today was examination day for the 'Functional Programming in Miranda' course at University College London, one of the last institutions to actually teach a course in Miranda.
Indeed, it's a great stepping stone to Haskell, with many of the important functional concepts but without some advanced (albeit useful) stuff like monadic programming.
One of the downsides is the ancient Mira console, which can output cryptic error messages, and which doesn't have command history out the box. Nevertheless, it's lightyears faster to start than GHCI, so good for learning.