"APL programs are normally interpreted and less often compiled. In reality,
most APL compilers translated source APL to a lower level language such as C,
leaving the machine-specific details to the lower level compiler. Compilation
of APL programs was a frequently discussed topic in conferences. Although some
of the newer enhancements to the APL language such as nested arrays have rendered
the language increasingly difficult to compile, the idea of APL compilation is
still under development today.
In the past, APL compilation was regarded as a means to achieve execution speed
comparable to other mainstream languages, especially on mainframe computers.
Several APL compilers achieved some levels of success, though comparatively
little of the development effort spent on APL over the years went to perfecting
compilation into machine code.
As is the case when moving APL programs from one vendor's APL interpreter to another,
APL programs invariably will require changes to their content. Depending on the compiler,
variable declarations might be needed, certain language features would need to be
removed or avoided, or the APL programs would need to be cleaned up in some way.
Some features of the language, such as the execute function (an expression evaluator)
and the various reflection and introspection functions from APL, such as the ability
to return a function's text or to materialize a new function from text, are simply
not practical to implement in machine code compilation."

И, на самом деле, это действительно очень выразительные языки.