Basic Language for Implementation of System Software

language (BLISS, or allegedly, "System Software

Implementation Language, Backwards") A language designed by

W.A. Wulf at CMU around 1969.

BLISS is an expression language. It is block-structured,

and typeless, with exception handling facilities,

coroutines, a macro system, and a highly optimisingcompiler. It was one of the first non-assembly languages

for operating system implementation. It gained fame for its

lack of a goto and also lacks implicit dereferencing: all

symbols stand for addresses, not values.

Another characteristic (and possible explanation for the

backward acronym) was that BLISS fairly uniformly used

backward keywords for closing blocks, a famous example being

ELUDOM to close a MODULE. An exception was BEGIN...END though

you could use (...) instead.

DEC introduced the NOVALUE keyword in their dialects to allow

statements to not return a value.

Versions: CMU BLISS-10 for the PDP-10; CMU BLISS-11,

BLISS-16, DEC BLISS-16C, DEC BLISS-32, BLISS-36 for

VAX/VMS, BLISS-36C.

["BLISS: A Language for Systems Programming", CACM

14(12):780-790, Dec 1971].

[Did the B stand for "Better"?]

(1997-03-01)