Ignored unencodeable characters mess up the terminal.

[judah]

In Terminal.app, with a UTF-8 encoding, use runghc examples/Test.hs to enter a line of text with several Greek letters in it.

Then, open a new terminal with the Western (ISO Latin 1) encoding and export LANG=fr_FR.ISO8859-1. Run Test.hs again and page through the old command history. The Greek letters are not encoded, so the redrawing commands mess up and delete the prefix "0:".

[judah]

Workaround is probably to encode the bad characters as '?'.

Need to investigate:

• Can we always assume that the byte '?' is a valid encoding of a character?
• Will this work with both encoding and decoding?

[judah]

The various encodings I've checked (UTF-8, EUC, KOI8, etc.) all encode '?' as the single byte 0x3f. So the above solution is fine (and is a desireable feature on its own).

Remember to update the Unicode wiki page to say that we only support encodings which use a single byte for both '\n' and '?'.

[judah]

This was fixed in 0.6.1.4.