Author:

• Name: Arch D. Robison
  Location: US - United States of America (United States)

To build:

    make all

Bugs and (Mis)features:

The current status of this entry is:

STATUS: INABIAF - please DO NOT fix

For more detailed information see 1989/robison in bugs.html.

To use:

    ./robison
    # enter valid expressions

Try:

    ./robison
    11x10
    # enter other expressions

    ./try.sh

    echo 100 / 100 | ./robison # <-- what happens here ?

NOTE: This program will very likely crash or break into tiny bits :-) if you feed it numbers with non-binary digits. This, as you might notice if you try one of the above commands, can happen with other input as well. If you wish to understand why this happens check the source code.

Judges’ remarks:

Sites with punch card facilities will be happy to note that the source deck can be re-collated with an ASCII sort.

Note that this program uses only a small subset of the constructs that the C language supports.

For an interesting document on APL, see https://computerhistory.org/blog/the-apl-programming-language-source-code/.

Author’s remarks:

This program is a handy picoAPL interpreter written in C--. It outputs the evaluation of an APL expression from standard input. Functions are limited to dyadic +,-,x, and unary -; numerals must be binary. Parentheses may be used for grouping. For example:

    101x111-100

prints:

    1111

That is 5x(7-4) is 15. (APL groups from right to left.) Extending it to the full APL language should be trivial.

The C-- language improves the C language by removing superfluous and confusing features: arithmetic, logical operations, shifts, relational operators, address-of, and flow control. In fact, the only expressions retained are function calls, indirection, array assignments, the ‘,’ operator, and sizeof. Despite these restrictions, the C-- program does arithmetic on arbitrarily large binary numbers.

To obtain a C-- reference, simply rip out the irrelevant pages from your K&R C manual. To obtain a C-- compiler, simply rip out the irrelevant bytes from your cc compiler.

Primary files

• robison.c - entry source code
• Makefile - entry Makefile
• robison.orig.c - original source code
• try.sh - script to try entry

Secondary files

• 1989_robison.tar.bz2 - download entry tarball
• README.md - markdown source for this web page
• .entry.json - entry summary and manifest in JSON
• .gitignore - list of files that should not be committed under git
• .path - directory path from top level directory
• index.html - this web page

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