If data is so big that parsing is a bottleneck, that seems like the wrong case for YAML. It's good for hand-edited and human-readable config files, and it's fast enough for that.
foo: 80:80
bar: 22:22
baz: 22.22
What's the value of foo? It's the string "80:80". What's the value of baz? The float 22.22 What's the value of bar? The integer 1342.I rest my case about both readability and writability.
I know zero toml (don't even know what toml stands for) but I'm pretty sure you meant the value of bar is the string 22:22 based on foo.
That said, I've never run up against this myself - in the face of potential ambiguity I attempt to be explicit, and surround it in quotes to be explicit string.
TOML itself is going through its own growth pains brought on by a rather sizable spec. For example:
>>> pytoml.loads("foo = 20:20:20")
[...]
pytoml.core.TomlError: <string>(1, 9): msg