There is a bug in Dec2001 Hugs (and earlier releases too) which causes the Prelude function `interact' to behave unexpectedly - the user's input is not echoed to the screen as she types it. A patch is attached which solves the problem.
Thanks, this is a long-standing and known feature of Hugs' interact implementation, so before possibly bringing it into line with what Haskell 98 tells us how `interact' ought to behave regarding echoing of input, it would be prudent to first check whether anyone depends on the current behaviour. In particular, are there 'important' resources (e.g., textbooks and tutorials) based around Hugs98 that depend on the current non-echoing behaviour?
Bird (2nd ed) makes use of the non-echoing interact, and describes another, programmed, solution to restore echoing, all on a single page (pp.230). Regards, Malcolm