Haskell Programs
By selecting Open... you can either open an existing Haskell program or create a new one (giving its name). All Haskell files are required to have the suffix .hs.

In HEAT you cannot explicitly save the edited program. Every time you compile or close a program, open a new program or close HEAT, the program is automatically saved. HEAT also makes a backup with suffix .hs~.

If you open a new program while editing another, the currently edited program is closed (and saved).