Bugs/wishes arising from the February 2002 TraceFest.

hat-explore
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B.  The = key does not always give a result.
B.  The = key sometimes gives a result which is not in fully evaluated form.
B.  Pattern match failure sometimes has a location beyond the end of
      the .hat file. (FIXED)
B.  Pretty-printing of list expressions comma-separated in square brackets
      sometimes has an incorrect inner open '['.  (There is of course no
      matching close ']'.)  (FIXED)
B.  The upper part of the display is blanked when the current expression
      causes previous expressions to scroll upwards, and the topmost
      expression is not exactly at the start of the page.
W.  Unevaluated expressions should be shown (by default) as _ rather than
      in full, just like in hat-observe.
W.  We need to see the definition source reference as well as the
      usage source reference.  Maybe 'S' for defn, 's' for usage.
W.  A status line at the bottom which gives information such as
      'no source reference', or 'file not found', or 'hat-observe started'
      would be useful.
W.  When calling out to hat-observe, Koen expected to see only
      applications of the selected function from the currently selected
      call site, but instead he got all applications throughout the program.
W.  Click on a position in the source reference viewer to call hat-observe
      on a specific call site?  This would give a facility rather like in
      HOOD, where a specific call site is annotated.
W.  A long character string gets chopped at a default depth, which means
      it appears as a cons list rather than a quoted string.  It would be
      better always to show a (fully evaluated) string as a string.
W.  An option to always show equations without needing to press the = key.

hat-observe
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B.  The 'count' command counts unique-ified reductions, which is not useful
      at all.  The number of actual reductions would be better.
W.  The 'show' command could (optionally) show reduction counts for each
      identifier.
W.  It can be difficult to narrow down the number of equations shown by
      specifying patterns.  One suggestion is to permit a pattern on the
      RHS of the 'in', e.g. observe f 1 in g 2.
W.  The algorithm for cutting off an expression at a particular depth
      tends to produce `striped' output.  An application of a cut to
      a sequence of cuts would be better shown as a single cut.

hat-detect
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B.  If hat-detect is called from another tool, and it does not find a bug,
      it terminates and the window disappears immediately.

general
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W.  The command syntax between the three tools should be as uniform as
      possible.
W.  Using ':' as a prefix for commands (like in Hugs) would be nice.  Some
      users automatically type ':q' for instance!
W.  A CAF definition which is a higher-order function (e.g. a composition
      chain) does not trace nicely.  It is currently necessary to 'observe'
      some of the inner calls before it is possible to 'explore' them.
      And often, it is not possible even to 'observe' the inner calls.
      Koen wondered if untrusting the composition operator (.) would
      allow us to see these inner calls better.
W.  Ralf would like a "guided tour" tutorial with examples to help
      introduce beginners to the tools.  Especially important is to
      explain the intuition or strategy behind which tool to use in what
      situations.
W.  Some people would like to animate reductions forwards rather than
      trace them backwards.  (This should be possible in the new
      file format.)
W.  Some overall co-ordination of the different windows could be helpful,
      in order to keep track of what was called from where.  Particularly
      to shut down all the windows belonging to one branch of the session
      without shutting down others.
