A practical guide to compiling Prolog predicates to self-contained AWK scripts using UnifyWeaver’s AWK target.
This book teaches you how to use UnifyWeaver to generate portable AWK scripts from Prolog predicates. AWK is a powerful text-processing language available on virtually every Unix-like system, making it ideal for data pipelines and log analysis.
Introduction to the AWK target, installation verification, and your first compiled script.
Learn to compile Prolog facts to AWK associative arrays and filter data with constraints.
Compile single and multiple rules with arithmetic and logical constraints.
Use built-in aggregation operations: sum, count, max, min, and avg.
Compile tail-recursive predicates to efficient AWK while loops.
Use the match/2, match/3, and match/4 predicates for regex operations.
Real-world examples: log analysis, data transformation, and pipeline integration.
| Feature | Description |
|---|---|
| Facts | Compiled to AWK associative arrays |
| Single Rules | Direct translation with constraint evaluation |
| Multiple Rules | Combined with union-style logic |
| Aggregations | sum, count, max, min, avg operations |
| Tail Recursion | Compiled to efficient while loops |
| Regex Matching | Full support via match/2, match/3, match/4 |
| Input Formats | TSV, CSV, JSONL record formats |
The AWK target supports multiple input formats:
% Tab-separated values (default)
compile_predicate_to_awk(pred/2, [record_format(tsv)], AWK)
% Comma-separated values
compile_predicate_to_awk(pred/2, [record_format(csv)], AWK)
% JSON Lines (one JSON object per line)
compile_predicate_to_awk(pred/2, [record_format(jsonl)], AWK)
% Custom field separator
compile_predicate_to_awk(pred/2, [field_separator(':')], AWK)
Prolog predicate:
high_salary(Name, Salary) :-
employee(Name, _, Salary),
Salary > 50000.
Compile to AWK:
?- compile_predicate_to_awk(high_salary/2, [], AWK),
write_awk_script('high_salary.awk', AWK).
Run the script:
awk -f high_salary.awk employees.tsv
The AWK target is designed for stream processing and has some constraints:
These limitations are inherent to AWK’s streaming model and are not bugs.
This educational content is dual-licensed under MIT (code) and CC-BY-4.0 (documentation).