Let me explain my problem by comparison. In Common Lisp I could split package definitions to several files, it was enough to declare in each of them that it's in-package and load them.
However in Guile Scheme it looks like I should define-module, separate for each file? Well I still can load some files like in CL and it looks like working, define-modules seems not limited to a single file it is located in like in CL, but I get warnings about undefined names (those that are defined in loaded files), so it gives me feeling that it's not what Guile expects. Is there (1) some way of splitting module across several files like in CL, or (2) should I stick to use-module autoload feature and define-module for each file separatelly?
Indeed in Guile you can load inside a define-module but it will report unbound variable at compile time.
The idiomatic way is the define-module in every file:
;; in earth-software-system.scm
(define-module (earth-software-system))
(use-modules (earth-software-system bullet-train))
(use-modules (srfi srfi-9))
(re-export bullet-train) ;; possibly re-exporting imported bindings
...
Then in earth-software-system/bullet-train.scm you can have:
;; in earth-software-system/bullet-train.scm
(define-module (earth-software-system bullet-train))
(use-modules (srfi srfi-9))
(define-public bullet-train 42)
...
Mind the fact that define-public and a single import per use-modules is not widespread. Here is an example from GNU Guix project that rely on define-module to import and export:
(define-module (guix cpio)
#:use-module ((guix build utils) #:select (dump-port))
#:use-module (srfi srfi-9)
#:use-module (srfi srfi-11)
#:use-module (rnrs bytevectors)
#:use-module (rnrs io ports)
#:use-module (ice-9 match)
#:export (cpio-header?
make-cpio-header
file->cpio-header
file->cpio-header*
write-cpio-header
read-cpio-header
write-cpio-archive))
Also nowadays I prefer the import form which is more easy to the mind that use-modules:
;; in earth-software-system.scm
(define-module (earth-software-system))
(import (prefix (earth-software-system bullet-train) 'bt:)
(import (srfi srfi-9))
(re-export bt:bullet-train) ;; possibly re-exporting imported bindings
...
The prefix syntax is also more easy to the mind than the equivalent using use-modules. This is inspired from R6RS library form and R7RS define-library form. I do not recommend to use library form in Guile since it doesn't report lines correctly.
GNU Guile allow to import forms even if they are not exported using the ## syntax for instance to test some tricky behavior.
You might replace load with include but I never used it in Guile
Related
Imagine a code generator which reads an input file (say a UML class diagram) and produces an arbitrary number of source files which I want to be handled in my project. (to draw a simple picture let's assume the code generator just produces .cpp files).
The problem is now the number of files generated depends on the input file and thus is not known when writing the CMakeLists.txt file or even in CMakes configure step. E.g.:
>>> code-gen uml.xml
generate class1.cpp..
generate class2.cpp..
generate class3.cpp..
What's the recommended way to handle generated files in such a case? You could use FILE(GLOB.. ) to collect the file names after running code-gen the first time but this is discouraged because CMake would not know any files on the first run and later it would not recognize when the number of files changes.
I could think of some approaches but I don't know if CMake covers them, e.g.:
(somehow) define a dependency from an input file (uml.xml in my example) to a variable (list with generated file names)
in case the code generator can be convinced to tell which files it generates the output of code-gen could be used to create a list of input file names. (would lead to similar problems but at least I would not have to use GLOB which might collect old files)
just define a custom target which runs the code generator and handles the output files without CMake (don't like this option)
Update: This question targets a similar problem but just asks how to glob generated files which does not address how to re-configure when the input file changes.
Together with Tsyvarev's answer and some more googling I came up with the following CMakeList.txt which does what I want:
project(generated)
cmake_minimum_required(VERSION 3.6)
set(IN_FILE "${CMAKE_SOURCE_DIR}/input.txt")
set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS "${IN_FILE}")
execute_process(
COMMAND python3 "${CMAKE_SOURCE_DIR}/code-gen" "${IN_FILE}"
WORKING_DIRECTORY ${PROJECT_BINARY_DIR}
INPUT_FILE "${IN_FILE}"
OUTPUT_VARIABLE GENERATED_FILES
OUTPUT_STRIP_TRAILING_WHITESPACE
)
add_executable(generated main.cpp ${GENERATED_FILES})
It turns an input file (input.txt) into output files using code-gen and compiles them.
execute_process is being executed in the configure step and the set_property() command makes sure CMake is being re-run when the input file changes.
Note: in this example the code-generator must print a CMake-friendly list on stdout which is nice if you can modify the code generator. FILE(GLOB..) would do the trick too but this would for sure lead to problems (e.g. old generated files being compiled, too, colleagues complaining about your code etc.)
PS: I don't like to answer my own questions - If you come up with a nicer or cleaner solution in the next couple of days I'll take yours!
If I want to optionally require a module at runtime, I can use [dynamic-require'1. This works great if I want to require a package that has been installed, for example:
(dynamic-require 'racket/match 'match)
This will (provided I have racket/match installed), require racket/match and evaluate to the match binding in that library.
However, I run into trouble when I want to require a local, non installed module. Let's say I have some module called eat.rkt, which provides one function: bite:
#lang racket ;; eat.rkt
(provide bite)
(define (bite) "Nom nom")
Now lets say we want to make a lunch.rkt module that requires eat.rkt, and calls the function. Furthermore, lets suppose I put them in the same directory:
#lang racket ;; lunch.rkt
(require "eat.rkt")
(bite) ; => Nom Nom
This is fine because I used static require, but this falls apart when I want to do a dynamic-require:
#lang racket ;; lunch2.rkt
(define bite (dynamic-require "eat.rkt" 'bite)
(bite) ; => Nom Nom
While this appears to be fine, it turns out that the module required by dynamic-require is NOT required based on the module's path, but on current-directory. So, if I run the program in the directory the module is defined, that's fine, but if I'm in another directory, everything breaks:
$ racket lunch2.rkt
"Nom Nom"
$ cd snacks/
$ racket ../lunch2.rkt
; default-load-handler: cannot open module file
Obviously I could just change the current-directory to this module's directory if I know where it is. But if I don't know this module's path, is there any way to get it? Or, more directly, is it possible to dynamic-require a module relative to the requiring's module path?
The define-runtime-path form defines a path that will be available at runtime and is independent of the current-directory. Use it to define the path to the module you want to require dynamically, for example:
#lang racket
(require racket/runtime-path)
(define-runtime-path eat "eat.rkt")
(dynamic-require eat 'bite)
The easiest way to dynamic-require a module relative to the current module path (which is to say the path where the module is saved), is to get that module path and append it your relative module.
You can do this with #%variable-reference and variable-reference->module-path-index. (You may also want to use variable-reference->resolved-module-path for other situations, but we will not do it here.) Composing these two functions gives us a module-path-index? to the module being defined. (Or in general, the module that the #%variable-reference came from.)
So, we can a variable like:
(define here (variable-reference->module-path-index (#%variable-reference)))
Now all that is left is to compose this here path with the relative path to the module we want to require. We are looking for the module path analogy of build-path, if you will.
It turns out that the function we are looking for is: module-path-index-join, which takes a base path and a relative path and appends them together. The result will look something like:
(module-path-index-join "eat.rkt" here)
(Yes, it is backwards of what you would expect from build-path, but the base path comes second for this function.)
The resulting module, lunch3.rkt looks like:
#lang racket
(define here (variable-reference->module-path-index (#%variable-reference)))
(define bite (dynamic-require (module-path-index-join "eat.rkt" here) 'bite))
And now lunch3.rkt will require eat.rkt relative to where its defined, not based on the current-directory:
$ racket lunch3.rkt
"Nom Nom"
$ cd snacks/
$ racket ../lunch3.rkt
"Nom Nom"
Thank you to Matthew Flatt for helping with this answer.
I tried to import System.Directory in my Frege program (In Eclipse) in order to use functions as getDirectoryContent, etc., and it writes me this error :
Could not import module frege.system.Directory (java.lang.ClassNotFoundException: frege.system.Directory)
What do I have to do ?
It is because the module frege.system.Directory doesn't exist in Frege. A good way to find out about a module is to use Hoogle for Frege at this URL: http://hoogle.haskell.org:8081. If we search for that module there, we can see that it doesn't list any module as opposed to, say, if you search for frege.data.List, we would see the module in the result.
Now for the functions you need like getDirectoryContent, if you look at the search result for frege.system.Directory, the first result is about processes and the third and fourth results are about jars and zip files. If you click on the second result, it would open the module frege.java.IO and you can see some relevant functions that might be useful for you (list for example). However the Haskell module you are trying to find is not yet ported to Frege but it should, of course, be possible to port that module backed by native Java implementations.
Update for OP's comment
Here is a simple snippet to return the files under a given directory:
ls :: String -> IO [String]
ls dir = do
contents <- File.new dir >>= _.list
maybe (return []) (JArray.fold (flip (:)) []) contents
Regarding createTempFile, the following works for me:
frege> File.createTempFile "test.txt"
String -> STMutable RealWorld File
How can I ensure that all modules (and ideally also all other files that have been loaded or included) are up-to-date? When issuing use_module(mymodule), SICStus compares the modification date of the file mymodule.pl and reloads it, if newer. Also include-ed files will trigger a recompilation. But it does not recheck all modules used by mymodule.
Brief, how can I get similar functionality as SWI offers it with make/0?
There is nothing in SICStus Prolog that provides that kind of functionality.
A big problem is that current Prologs are too dynamic for something like make/0 to work reliably except for very simple cases. With features like term expansion, goals executed during load (including file loading goals, which is common), etc., it is not possible to know how to reliably re-load files. I have not looked closely at it, but presumably make/0 in SWI Prolog has the same problem.
I usually just re-start the Prolog process and load the "main" file again, i.e. a file that loads everything I need.
PS. I was not able to get code formatting in the comments, so I put it here instead: Example why make/0 needs to guard against 'user' as the File from current_module/2:
| ?- [user].
% compiling user...
| :- module(m,[p/0]). p. end_of_file.
% module m imported into user
% compiled user in module m, 0 msec 752 bytes
yes
| ?- current_module(M, F), F==user.
F = user,
M = m ? ;
no
| ?-
So far, I have lived with several hacks:
Up to 0.7 – pre-module times
SICStus always had ensure_loaded/1 of Quintus origin, which was not only a directive (like in ISO), but was also a command. So I wrote my own make-predicate simply enumerating all files:
l :-
ensure_loaded([f1,f2,f3]).
Upon issuing l., only those files that were modified in the meantime were reloaded.
Probably, I could have written this also like — would I have read the meanual (sic):
l :-
\+ ( source_file(F), \+ ensure_loaded(F) ).
3.0 – modules
With modules things changed a bit. On the one hand, there were those files that were loaded manually into a module, like ensure_loaded(module:[f1,f2,f3]), and then those that were clean modules. It turned out, that there is a way to globally ensure that a module is loaded — without interfering with the actual import lists simply by stating use_module(m1, []) which is again a directive and a command. The point is the empty list which caused the module to be rechecked and reloaded but thanks to the empty list that statement could be made everywhere.
In the meantime, I use the following module:
:- module(make,[make/0]).
make :-
\+ ( current_module(_, F), \+ use_module(F, []) ).
This works for all "legal" modules — and as long as the interfaces do not change. What I still dislike is its verboseness: For each checked and unmodified module there is one message line. So I get a page full of such messages when I just want to check that everything is up-to-date. Ideally such messages would only show if something new happens.
| ?- make.
% module m2 imported into make
% module m1 imported into make
% module SU_messages imported into make
yes
| ?- make.
% module m2 imported into make
% module m1 imported into make
% module SU_messages imported into make
yes
An improved version takes #PerMildner's remark into account.
Further files can be reloaded, if they are related to exactly one module. In particular, files loading into module user are included like the .sicstusrc. See above link for the full code.
% reload files that are implicitly modules, but that are still simple to reload
\+ (
source_file(F),
F \== user,
\+ current_module(_, F), % not officially declared as a module
setof(M,
P^ExF^ExM^(
source_file(M:P,F),
\+ current_module(M,ExF), % not part of an official module
\+ predicate_property(M:P,multifile),
\+ predicate_property(M:P,imported_from(ExM))
),[M]), % only one module per file, others are too complex
\+ ensure_loaded(M:F)
).
Note that in SWI neither ensure_loaded/1 nor use_module/2 compare file modification dates. So both cannot be used to ensure that the most recent version of a file is loaded.
Does OCaml have a way to get the current file/module/script name? Something like:
C/C++'s argv[0]
Python's sys.argv[0]
Perl/Ruby's $0
Erlang's ?FILE
C#'s ProgramName.Environment.CommandLine
Factor's scriptname/script
Go's os.Args[0]
Haskell's System/getProgName
Java's System.getProperty("sun.java.command").split(" ")[0]
Node.js's __filename
etc.
I don't know anything about OCaml but some googling turned up
Sys.argv.(0)
See http://caml.inria.fr/pub/docs/manual-ocaml/manual003.html#toc12
I presume you are scripting in OCaml. Then Sys.argv.(0) is the easiest way to get the script name. Sys module also provides Sys.executable_name, but its semantics is slightly different:
let _ = prerr_endline Sys.executable_name; Array.iter prerr_endline Sys.argv;;
If I run the above line, putting the line in test.ml, by ocaml test.ml hello world, I have:
/usr/local/bin/ocaml - executable_name
test.ml - argv.(0)
hello - argv.(1)
world - argv.(2)
So OCaml toplevel does something fancy against argv for you.
In general, obtaining the current module name in OCaml is not easy, from several reasons:
ML modules are so flexible that they can be aliased, included into other modules, and applied to module functors.
OCaml does not embed the module name into its object file.
One probably possible workaround is to add a variable for the module name by yourself, like:
let ml_source_name = "foobar.ml"
This definition can be probably auto inserted by some pre-processing. However, I am not sure CamlP4 can have the file name of the currently processing source file.
If your main purpose is simple scripting, then of course this pre-processing is too complicated, I am afraid.
let _ =
let program = Sys.argv.(0) in
print_endline ("Program: " ^ program)
And posted to RosettaCode.
In OCaml >= 4.02.0, you can also use __FILE__ to get the filename of the current file, which is similar to Node's __filename and not the same as Sys.argv.(0).