als_system/1
Module: builtins
als_system/1 — Provides system environmental information.
sys_env/3 — Provides brief system environmental information.
FORMS
als_system(INFO_LIST)
sys_env(OS, OS_Variation, Processor)
DESCRIPTION
Portable programs which interact with the operating system must take account of the variations in the system environment. als_system/1 provides a method of achieving this goal. When the ALS Prolog system initializes itself, the underlying C substrate asserts a single fact
als_system(INFO_LIST)
in the module builtins in the Prolog database. The argument of this fact is a list of equations of the form
property = value
Each property appears at most once. The properties and their possible values are listed in the table below.
| Property Tag | Value Examples |
|---|---|
| os | unix, dos, macos, mswins32, vms |
| os_variation | (unix) : solaris2.4 |
| processor | port_thread, port_byte, i386, m68k, m88k, sparc, powerpc |
| manufacturer | generic, sun, motorola, dec, |
| prologVersion | nnn-mm |
| wins | nowins, motif, macos, … |
For most purposes, knowing the operating system(OS), and possibly the Processor, is what matters. Consequently, another small fact,
sys_env(OS, OS_Variation, Processor)
is asserted during initialization, recording the values of the os, the os_variation, and the processor properties from the als_system list description.
EXAMPLES
On a Sun SPARC running Solaris 2.4, TTY portable version :
?- als_system(X).
X = [os = unix, os_variation = solaris2.4, processor = port_thread,
manufacturer = generic, prologVersion = '1-76 ', wins = nowins ]