Bliss (for Basic Language for Implementation of System Software) is a system programming language created around 1970. Like BCPL, it is typeless, having a ‘word’ (a sequence of bits) as its only kind of value. Unlike BCPL, Bliss is expression-oriented.

Distinguishing features of Bliss are it having an exception handling mechanism, coroutines, macroprocessing, and the lack of goto statement. A number of constructs that are built in most programming languages are made available in Bliss through syntax macros.

The language is notable for requiring that variable dereference is always done explicitly. A variable name itself represents a pointer to that variable, and to retrieve the value of the variable one has to apply an operator (a dot).

Bliss is known to have been used on some of Digital Equipment's PDP and VAX machines. The original compiler was famous for its extensive use of optimizations, but that was at the expense of portability: in fact, a number of the optimizing techniques used were machine-specific, which made the compiler nonportable. Many programs written in Bliss were also nonportable.

With the appearance and growing popularity of C Bliss's use started to fade away. One reason for that was the lack of portability: even for machines of the same brand but of different series different compilers were needed. The language was eventually discontinued somewhere in the 1980s.

Links of Relevance:

Bliss Language Guide from Digital Equipment.

BLISS Language Reference Manual from Digital Equipment.