@main[]

1. ^show[+]
2. ^show[-]
3. ^show[ + ]
4. ^show[ - ]

5. ^show[-1.]
6. ^show[-1.1]

another exception, inside pa_ato_any, without even sign:
d2. ^try-catch{^date::create[ +4000000000-12-01]}
d3. ^try-catch{^date::create[ -8000000000-12-01]}

@show[s]
^try-catch{^s.int[]} ^try-catch{^s.double[]}