$ perl5.14.1 junk
Compiling REx "-?\p{Nd}"
synthetic stclass "ANYOF{i}[\-][{non-utf8-latin1-all}{unicode}{outside bitmap}+utf8::Nd]".
Final program:
   1: CURLY {0,1} (5)
   3:   EXACT <-> (0)
   5: ANYOF[{unicode}{outside bitmap}+utf8::Nd] (16)
  16: END (0)
stclass ANYOF{i}[\-][{non-utf8-latin1-all}{unicode}{outside bitmap}+utf8::Nd] minlen 1
Matching REx "-?\p{Nd}" against "1"
Matching stclass ANYOF{i}[\-][{non-utf8-latin1-all}{unicode}{outside bitmap}+utf8::Nd] against "1" (1 bytes)
   0 <> <1>                  |  1:CURLY {0,1}(5)
                                  EXACT <-> can match 0 times out of 1...
   0 <> <1>                  |  5:  ANYOF[{unicode}{outside bitmap}0-9...+utf8::Nd](16)
   1 <1> <>                  | 16:  END(0)
Match successful!
Matches
Freeing REx: "-?\p{Nd}"