Another data point on the idea of languages implemented in layers, consider this... ("why you should care as a programmer about the study of programming languages")... (pdf)... Dan Friedman's talk at UNAM, Mexico, on April 27, 2001... quoting his student Jonathan Sobel:
“That was the amazing part: I had produced a program that I could not have written, and in any case would not have wanted to write.”Sobel wrote a program in a simple, direct style using Scheme and then applied several transformations, from Scheme to Scheme, each a fairly simple transformation. The final transformation was ready to be translated into a C program using another simple transformation.
The efficient C program does not have to be maintained. Just the original, simple Scheme program. Probably programming in C itself (or Java or Scala) is a kind of premature optimization.