library(iso)

Description

Overview

Apart from the functionality described in ISO 13211-1, an ISO-compatible subset of native ECLiPSe functionality is also available. For a strict implementation of ISO 13211-1 without any extensions, see library(iso_strict).

This is one of three libraries providing different degrees of ISO compatibility:

iso_strict

Aims to be fully ISO compliant, and represents the 'strict mode' required by the standard.

iso

Aims to be fully ISO compliant, but also includes ECLiPSe functionality that does not conflict with the standard.

iso_light

Provides the essence of ISO features without aiming for full conformance (in particular with respect to error handling), and may include ECLiPSe extensions that go beyond what the letter of the standard allows. Also useful for importing individual ISO features into a program that is otherwise written in ECLiPSe dialect.

Usage

    :- module(myisomodule, [], iso).
    

Alternatively, in order to use ISO-Prolog without having different modules, one can invoke eclipse with a "-L iso" command line option, or set the ECLIPSEDEFFAULTLANGUAGE environment variable to 'iso'. This will launch eclipse with a default module accepting 'iso' language instead of the usual 'eclipse_language'.

Specification of implementation defined features

5.5.11 Reserved atoms

The functors no_macro_expansion/1, of/2, with/2, and with_attributes/2 are reserved

6.5 Processor characted set

The PCS is the ISO 8859-1 character set. Classification of extended characters: 7f-a0 layout; a1-bf, d7, f7 graphic; c0-d6, d8-f6, f8-ff alphanumeric.

6.6 Collating sequence

The collating sequence is that of the ISO 8859-1 character set

7.1.2.2 Character codes

Each character maps to a corresponding byte

7.1.4.1 Characters

As in the ISO 8859-1 character set

7.2.1 Variable term order

Older variables precede newer variables

7.4.2.4,5 op/3 and char_conversion/2

An operator or character-conversion defined in a directive is effective at runtime, and only in the module in which it occurs

7.4.2.6 initialization/1

Initialization goals are executed in the order in which they occur in the Prolog text

7.4.2.7 include/1

The argument is a file name atom according to ECLiPSe's canonical file name syntax, or a term of the form library(atom)

7.4.2.8 ensure_loaded/1

The argument is a file name atom according to ECLiPSe's canonical file name syntax, or a term of the form library(atom). A file will be loaded on the first occurrence of ensure_loaded/1 in a prolog text, and if the file has been modified since the time it was first loaded.

7.4.2.7 set_prolog_flag/2

Flag setting are effective at runtime and globally (except for a few module-local flags in non-strict mode, see set_flag/2)

7.5.1 Preparing for execution

See the eclipse_language built-ins, menu items and command line options for compiling, loading and module handling, and also the instructions for using library(iso) or library(iso_strict)

7.7.1,3 Execution and Initialization

See the general ECLiPSe facilities, i.e. toplevel, graphical user interface and command line options

7.10.1 Sources and sinks

See open/3,4

7.10.2.6 Text streams

Text streams are very similar to binary streams, no characters are implicitly inserted or removed. The nl/0,1 predicates emit an operating system and device dependent newline sequence.

7.10.2.8,11 Stream positions

File, string, and null streams can be (re)positioned

7.10.2.9 End position of a stream

The end position of a stream is the same as the position that a character appended to the stream would have

7.10.2.11 Stream options

The default eof_action is error

7.10.2.13 Stream properties

File names are atoms according to ECLiPSe's canonical file name syntax.

7.11 Flags

Fixed values: bounded=false, min_integer and max_integer fail, integer_rounding_function=toward_zero, max_arity=unbounded, char_conversion=off. Default values: double_quotes=chars, debug=off. If debug=on, the ECLiPSe tracer is active. In non-strict mode, there is an additional flag max_predicate_arity, which indicates the limit on predicate arity (there is no limit on term arity).

7.12.1 Effect of an error

The implementation defined error term argument is normally the predicate indicator of the culprit goal. For syntax errors, it is a term describing the error location.

8.15.4 call/N

The maximum N is given by the flag max_predicate_arity (255)

8.17.1 set_prolog_flag/2

The admissible flag values are the ones defined by ISO-Prolog (for iso_strict), plus those accepted by ECLiPSe's set_flag/2 (for iso)

8.17.3,4 halt/0,1

Exits the OS process with the given return code (or 0)

9 Evaluable functors

The 'exceptional values' are realized as follows: 'float_overflow' leads to a floating point infinity result; 'underflow' leads to a floating point denormalized value result; 'zero_divisor' leads to a floating point infinity result in the case of floats, or an evaluation_error(zero_divisor) in the case of integers; 'int_overflow' does not occur and might lead to running out of memory instead.

9.3 Other arithmetic operations

When min/2 or max/2 are used with mixed integer and float arguments, the integer is coerced to float, and the result computed by comparing two floats

9.4 Bitwise arithmetic operations

The bitwise arithmetic operations behave as if operating on an unlimited length two's complement representation

Implementation specific features

7.10.2.11 Stream options

For additional stream options, see open/4

7.10.2.12 Options on stream closure

No additional options

7.10.2.13 Stream properties

For additional stream properties, see get_stream_info/3

7.10.3 Read options

For additional read options, see read_term/3

7.10.4 Write options

For additional stream options, see write_term/3

7.11 Flags

For additional Prolog flags, see get_flag/2

9 Evaluable functors

For additional evaluable functors, see is/2

• Directives, unless conflicting
• Built-in predicates, unless conflicting
• Definite Clause Grammar Rules
• Delay Clauses
• Strings (with ISO-compatible back-quote syntax)
• Rational and Bounded Real numbers
• Array and Structure notation
• Attributed Variables

Remaining deviations from Standard

1. The char_conversion flag is always off, meaning that character conversion is not applied to prolog texts or on term input. However, char_conversion/2 and current_char_conversion/2 predicates are operational.

About

• Author: Joachim Schimpf, Coninfer Ltd
• Copyright © Joachim Schimpf, Coninfer Ltd
• Date: $Date: 2017/08/23 12:02:50 $

See Also