Last year I intended to write an update on my use of hledger, but that was waylaid for various reasons and I need to revisit how (if) I'm using it, so that's put off for longer. I do want to mention one contribution I made upstream: a dark theme for the UI, and some unfinished work on consistent colours.

Consistent terminal colours are an interesting issue: the most common terminal colour modes (8 and 256) use indexing into a palette, but the definition of the colours is ambiguous: the 8-colour palette is formally specified by ANSI as names (red, green, etc.); the 256-colour palette is effectively defined by xterm (a useful chart) but I'm not sure all terminal emulators that support it have chosen the same colour values.

A consequence of indexed-colour is that the end-user may redefine what the colour values are. Whether this is a good thing or a bad thing depends on your point of view. As an end-user, it's attractive to be able to tune the colour scheme; but as a software author, it means you have no real idea what your users are going to see, and matters like ensuring contrast are impossible.

Some terminals support 24-bit "true" colour, in which the colours are specified as an RGB triplet. Using these mean the software author can be reasonably sure all users will see the same thing (for a fungible definition of "same"), at the cost of user configurability. However, since it's less well supported, we start having to worry about fallback behaviour.

In the case of hledger-ui, which provides several colour schemes, that's probably OK, because the user configurability is achieved by choosing one of the schemes. (or writing your own, in extremis). However, the dark theme I contributed uses the 8-colour palette, in common with the other themes, and my explorations into using predictable colours are unfinished.

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