リスプ－１。

Whats your favorite Scheme standard nowadays, /prog/? Are you coding from a standard or implementation specific?

        1975 "Scheme: an interpreter for extended lambda calculus"
3 yrs   1978 RRS
     << 1984 SICP >>
7 yrs   1985 RRRS
1 yr    1986 R3RS
5 yrs   1991 R4RS
     << 1996 SICP 2nd E >>
7 yrs   1998 R5RS
     << 2001 HtDP >>
9 yrs   2007 R6RS
5 yrs   2012 R7RS-SmL-draft6

I had hopes for R7RS, but they're too concerned with backwards compatibility to fix the mistakes R5RS made/inherited from R4RS and the IEEE standard. My hopes for R7RS died when they decided to stay with SRFI-1 records, and left after the unspecified value vs values argument.
With the right abstractions, backwards compatibility could be achieved anyway, but NO!, we must continue to get things wrong.

So, Racket.