4.3.3 Quick load files

SWI-Prolog supports compilation of individual or multiple Prolog source files into‘Quick Load Files'. A‘Quick Load File' (.qlf file) stores the contents of the file in a precompiled format.

These files load considerably faster than source files and are normally more compact. They are machine-independent and may thus be loaded on any implementation of SWI-Prolog. Note, however, that clauses are stored as virtual machine instructions. Changes to the compiler will generally make old compiled files unusable.

Quick Load Files are created using qcompile/1. They are loaded using consult/1 or one of the other file-loading predicates described in section 4.3. If consult/1 is given an explicit .pl file, it will load the Prolog source. When given a .qlf file, it will load the file. When no extension is specified, it will load the .qlf file when present and the .pl file otherwise.

qcompile(:File)

Takes a file specification as consult/1, etc., and, in addition to the normal compilation, creates a Quick Load File from File. The file extension of this file is .qlf. The basename of the Quick Load File is the same as the input file.

If the file contains‘:- consult(+File)’,‘:- [+File]’or‘:- load_files(+File, [qcompile(part), ...])’statements, the referred files are compiled into the same .qlf file. Other directives will be stored in the .qlf file and executed in the same fashion as when loading the .pl file.

For term_expansion/2, the same rules as described in section 2.11 apply.

Conditional execution or optimisation may test the predicate compiling/0.

Source references (source_file/2) in the Quick Load File refer to the Prolog source file from which the compiled code originates.

qcompile(:File, +Options)

As qcompile/1, but processes additional options as defined by load_files/2.^{bugOption processing is currently incomplete.}