predicates

README

predicates

import "github.com/guregu/predicates"

Native predicates for ichiban/prolog.

Prolog

Filesystem predicates use io/fs.FS.

Built-in replacements

• consult/1

library(files)

These predicates are intended to be compatible with Scryer Prolog's library(files). These use strings (lists of characters) for filenames.

• directory_files/2
• directory_exists/1
• file_exists/1

Lists

• is_list/1

Package taujson

These predicates are intended to be compatible with Tau Prolog's library(js). They are peculiar predicates that use opaque native objects for JSON conversion.

• json_atom/2
• json_prolog/2

Graduated

• between/3 made it into ichiban/prolog in v0.9.0!

Go

Package chars provides some convenience functions for working with Prolog strings.

License

BSD 2-clause. Includes code from ichiban/prolog (MIT license). See LICENSE.

Documentation

Index

• func IsList(t engine.Term, k func(*engine.Env) *engine.Promise, env *engine.Env) *engine.Promise
• type FS
  • func NewFS(fsys fs.FS, i *prolog.Interpreter) FS
  • func (ff FS) Consult(files engine.Term, k func(*engine.Env) *engine.Promise, env *engine.Env) *engine.Promise
  • func (ff FS) DirectoryExists(directory engine.Term, k func(*engine.Env) *engine.Promise, env *engine.Env) *engine.Promise
  • func (ff FS) DirectoryFiles(directory, files engine.Term, k func(*engine.Env) *engine.Promise, ...) *engine.Promise
  • func (ff FS) FileExists(file engine.Term, k func(*engine.Env) *engine.Promise, env *engine.Env) *engine.Promise
  • func (ff FS) Register()

Functions

func IsList

func IsList(t engine.Term, k func(*engine.Env) *engine.Promise, env *engine.Env) *engine.Promise

IsList (is_list/1) succeeds if the given term is a list.

is_list(@Term).

Types

type FS

type FS struct {
	// contains filtered or unexported fields
}

FS provides native file system predicates. Non-ISO predicates are intended to maintain compatibility with Scryer Prolog's library(files). See: https://github.com/mthom/scryer-prolog/blob/master/src/lib/files.pl

func NewFS

func NewFS(fsys fs.FS, i *prolog.Interpreter) FS

NewFS returns a collection of filesystem predicates tied to fsys and i.

func (FS) Consult

func (ff FS) Consult(files engine.Term, k func(*engine.Env) *engine.Promise, env *engine.Env) *engine.Promise

Consult (consult/1) reads and executes the given file (if given an atom) or files (if given a list of atoms). ".pl" will be automatically appended to the file names when needed. Throws an error if files is not an atom or list of atoms.

consult(+FileOrList).

func (FS) DirectoryExists

func (ff FS) DirectoryExists(directory engine.Term, k func(*engine.Env) *engine.Promise, env *engine.Env) *engine.Promise

DirectoryExists (directory_exists/1) succeeds if a directory exists at the path given by the string directory. Throws an error if directory is not a string.

directory_exists(+Directory).

func (FS) DirectoryFiles

func (ff FS) DirectoryFiles(directory, files engine.Term, k func(*engine.Env) *engine.Promise, env *engine.Env) *engine.Promise

DirectoryFiles (directory_files/2) succeeds if files is a list of strings that contains all entries (including directories) of directory, which must be a string. This is useful for obtaining a list of files and directories. Throws an error if directory is not a string.

directory_files(+Directory, -Files).

func (FS) FileExists

func (ff FS) FileExists(file engine.Term, k func(*engine.Env) *engine.Promise, env *engine.Env) *engine.Promise

FileExists (file_exists/1) succeeds if a file exists at the path given by the string file. Throws an error if file is not a string.

file_exists(+File).

func (FS) Register

func (ff FS) Register()

Register is a convenience method that registers all FS predicates with their default names. This will replace the default consult/1. To register these with custom names, use the interpreter's Register functions and pass a method reference instead.