[TUHS] Re: Perkin-Elmer Sort/Merge II vs Unix sort(1)

[Douglas McIlroy <douglas.mcilroy@dartmouth.edu>]

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All-in-one vs pipelined sorts brought to mind NSA's undeservedly obscure
dataflow language, POGOL, https://doi.org/10.1145/512927.512948 (POPL
1973). In POGOL one wrote programs as collections of routines that
communicated via named files, which the compiler did its best to optimize
away. Often this amounted to loop jamming or to the distributive law for
map over function composition. POGOL could, however, handle general
dataflow programming including feedback loops.

One can imagine a program for pulling the POGOL trick on a shell pipeline.
That could accomplish--at negligible cost--the conversion of a cheap demo
into a genuine candidate for intensive production use.

This consideration spurs another thought. Despite Unix's claim to build
tools to make tools, only a relativelly narrow scope of higher-order tools
that take programs as dara ever arose. After the bootstrapping B, there
were a number of compilers,  most notably C, plus  f77, bc, ratfor, and
struct. A slight variant on the idea of compiling was the suite of troff
preprocessors.

The shell also manipulates programs by composing them into larger programs.

Aside from such examples, only one other category of higher-order Unix
program comes to mind: Peter Weinberger's lcomp for instrumenting C
programs with instruction counts.

An offshoot of Unix were Gerard Holzmann's tools for extracting
model-checker models from C programs. These saw use at Indian Hill and most
notably at JPL, but never appeared among mainstream Unix offerings. Similar
tools exist in-house at Microsoft and elsewhere. But generally speaking we
have vey few kinds of programs that manipulate programs.

What are the prospects for computer science advancing to a stage where
higher-level programs become commonplace? What might be in one's standard
vocabulary of functions that operate on programs?

Doug

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