Wide-spectrum language


A wide-spectrum language is a programming language designed to be simultaneously a low-level and a high-level language—possibly a non-executable specification language. Wide-spectrum languages are designed to support a programming methodology based on program refinement.
The concept was introduced by F. L. Bauer et al. in 1978:

...The program should then be developed step by step applying correctness
preserving transformations.... The development process
thus involves usually multiple reshapings....
Since most current programming languages do not contain
all the concepts needed for the formulation of the different
versions, the programmer is nowadays forced to
use different languages. To avoid the transition from
one language to another, it seems appropriate to have
one coherent language frame covering the whole spectrum
outlined above, i.e. a wide spectrum language.

The advantage of a single language rather than separate specification, high-level, and low-level languages is that the program can be incrementally refined, with intermediate versions retaining some higher-level and some lower-level constructs.
Bauer's group developed the CIP-L wide-spectrum language and the CIP-S program transformation system.