I have a program that uses the Bytes module from the Ocaml standard library and also opens the Core_kernel.Std module at the top of the file
open Core_kernel.Std
...
let let buf = Bytes.make bom_len '\x00' in
The problem I am having is that the latest version of Core_kernel introduced a new Bytes module that is shadowing the one from the standard library, which is resulting in a Unbound value Bytes.make compilation error.
Is there a way to solve this naming issue without getting rid of the open at the top of the file? If I did that it would require changing lots of things.
You could provide an alternative name for the Bytes module as such:
module B = Bytes
open Core_kernel.Std
let buf = B.make 10 '\x00'
and then do a search-replace in your code to change Bytes by B.
Another solution would be to avoid using open, but this would require a lot of changes in your code, I guess.
Core_kernel provides Caml module that binds everything that is available in standard library.
So, you could write this as
open Core_kernel.Std
...
let buf = Caml.Bytes.make bom_len '\x00' in
Unfortunately, Caml.Bytes is added only in 113.00.00 version that is not in OPAM yet.
Related
I am used to using the standard function print_int in OCaml, but when I open the library Base by Jane Street, as recommended in the book Real World OCaml, I obtain a deprecation warning:
utop # print_int;;
- : int -> unit = <fun>
utop # open Base;;
utop # print_int;;
Line 1, characters 0-9:
Alert deprecated: Base.print_int
- : int -> unit = <fun>
Even worse, when I build it with dune, as recommended in that book, warnings become errors. What should I do ? Replace print_int with printf "%i" ? or with Caml.print_int ? Both seem to work but look needlessly complicated. Something else ?
Thank you.
This is answered here: https://ocaml.janestreet.com/ocaml-core/v0.13/doc/base/index.html#using-the-ocaml-standard-library-with-base
Base is intended as a full stdlib replacement. As a result, after an open Base, all the modules, values, types, etc., coming from the OCaml standard library that one normally gets in the default environment are deprecated.
In order to access these values, one must use the Caml library, which re-exports them all through the toplevel name Caml: Caml.String, Caml.print_string, ...
This one's going to take a bit of explaining. Please bear with me.
What I Have
I have in my possession some Fortran source code and some binaries that have been compiled from that code. I did not do the compilation, but there is a build script that suggests G77 was used to do it.
As well as the Fortran stuff, there is also some Java code that provides users with a GUI "wrapper" around the binaries. It passes information between itself and the binaries via their input/output/error pipes. The Java code is very messy, and this way of doing things adds a lot of boilerplate and redundancy, but it does the job and I know it works.
What I Need
Unfortunately, I'd like to make some changes:
I want to create a new Python wrapper for the binaries (or, more precisely, extend an existing Python program to become the new wrapper).
I want to be able to compile the Fortran code as part of this existing program's build process. I would like to use gfortran for this, since MinGW is used elsewhere in the build and so it will be readily available.
The Problem
When I compile the Fortran code myself using gfortran, I cannot get the resulting binaries to "talk" to either the current Java wrapper or my new Python wrapper.
Here are the various ways of printing to the console that I have tried in the Fortran code:
subroutine printA(message)
write(6,*) message
end
subroutine printB(message)
write(*,*) message
end
subroutine printC(message)
use iso_fortran_env
write(output_unit,*) message
end
There are also read commands as well, but the code doesn't even get a change to execute that part so I'm not worrying about it yet.
Extra Info
I have to call gfortran with the -ffixed-line-length-132 flag so that the code compiles, but apart from that I don't use anything else. I have tried using the -ff2c flag in the vague hope that it will make a difference. It doesn't.
This stackoverflow post is informative, but doesn't offer me anything that works.
The relavant manual page suggests that printA should work just fine.
I'm working on Windows, but will need this to be multi-platform.
Juse in case you're intested, the Java code uses Runtime.getRuntime().exec("prog.exe") to call the binaries and then the various "stream" methods of the resulting Process object to communicate with them. The Python code uses equivalents of this provided by the Popen object of the subprocess module.
I should also say that I am aware there are alternatives. Rewriting the code in Python (or something else like C++), or making amendments so that is it can be called via F2Py have been ruled out as options. Using g77 is also a no-go; we have enough dependencies as it is. I'd like to be able to write to / read from the console properly with gfortran, or know that it's just not possible.
Hard to say without seeing more details from your Fortran and Python codes. The following pair of code works for me (at least under Linux):
Fortran program repeating its input line by line prefixed with line number:
program test_communication
use iso_fortran_env, stdout => output_unit, stdin => input_unit
implicit none
character(100) :: buffer
integer :: ii
ii = 1
do while (.true.)
read(stdin, *) buffer
write(stdout, "(I0,A,A)") ii, "|", trim(buffer)
flush(stdout)
ii = ii + 1
end do
end program test_communication
Python program invoking the Fortran binary. You can feed it with arbitrary strings from the console.
import subprocess as sub
print "Starting child"
proc = sub.Popen("./a.out", stdin=sub.PIPE, stdout=sub.PIPE)
while True:
send = raw_input("Enter a string: ")
if not send:
print "Exiting loop"
break
proc.stdin.write(send)
proc.stdin.write("\n")
proc.stdin.flush()
print "Sent:", send
recv = proc.stdout.readline()
print "Received:", recv.rstrip()
print "Killing child"
proc.kill()
I am trying to get Concurret ML run in SMLNJ. I saw a post about using CM.make to do this but I could not find CM.make file on my system. Please tell how to resolve this
Well, I can load the library directly. For instance, in my case I could do
sml /opt/smlnj/cml/src/cml.cm
Knowing where the library is located, you could use CM.make. For instance, in my REPL if I do
CM.make "/opt/smlnj/cml/src/cml.cm";
It loads the CML library. With either approach if I do:
val r = CML.version
I get:
val r = {date="September 15, 1997",system="Concurrent ML",version_id=[1,0,10]}
: {date:string, system:string, version_id:int list}
The CM library should already be available in your current installation of SML. I did not have to do anything special to load it.
See the SML/NJ FAQ in the section about loading libraries.
While compiling an OCaml application I get the following error:
File "/tmp/ocamlpp466ee0", line 308, characters 34-233:
Error: Signature mismatch:
...
The field `unlock' is required but not provided
The field `lock' is required but not provided
Command exited with code 2.
My guess is that the error is releated with the OCaml library Datalog (I've installed the version 0.3 from here) because the line 308 in the file is /tmp/ocamlpp466ee0 the first one in the following code
module Logic = Datalog.Logic.Make(struct
type t = atom
let equal = eq_atom
let hash = hash_atom
let to_string a = Utils.sprintf "%a" pp_atom a
let of_string s = atom_of_json (Json.from_string s)
end)
I would really appreciate if someone could help me to know what I am doing wrong.
Moreover, I would like to undestand why the file /tmp/ocamlpp466ee0 is generated each time I execute 'make'? I tried to understand by reading the Makefile but I did not succeed.
I think that something have changed in Datalog library and in some version > 0.3 functor Datalog.Logic.Make requires module argument with values lock and unlock declared. So, it's version problem.
About temporary file. As you can see, its name consists of ocaml literal, pp which means preprocessor and some number. Preprocessors in OCaml usually work this way: they read input source file and write output source files. That's why some temporary files are created.
I would like to know if in Fortran it is possible to use just a single command (with options/specifiers) to do the following:
open a file if it exists and append some data
(this can be done with: open(unit=40,file='data.data',Access = 'append',Status='old') but if the file does not exist a runtime error is issued)
create the file if it does not exist and write some data.
I am currently using inquire to check whether the file exist or not but then I still have to use the open statement to append or write data.
As far as I am aware of, the only safe solution is to do the way you're already doing it, using different open statements for the different cases:
program proba
implicit none
logical :: exist
inquire(file="test.txt", exist=exist)
if (exist) then
open(12, file="test.txt", status="old", position="append", action="write")
else
open(12, file="test.txt", status="new", action="write")
end if
write(12, *) "SOME TEXT"
close(12)
end program proba
You may be interested in my Fortran interface library to libc file system calls (modFileSys), which could at least spare you the logical variable and the inquire statement by querying the file status directly:
if (file_exists("test.txt")) then
...
else
...
end if
but of course you can program a similar function easily yourself, and especially it won't save you from the two open statements...
open(61,file='data.txt',action='write',position='append')
write(61,*) 'hey'
close(61)
This will append to an existing file, otherwise create and write. Adding status='unknown' would be equivalent.
if you replace the status from 'old' to 'unknown' then you will not get the run time error if the file exists or now.
Thanks
In open statement add the attribute access as follows;
Open(unit=031,file='filename.dat',form='formatted',status='unknown',access='append')
The above statement will open the file without destroying old data and write command will append the new lines in the file.
The simplest solution for fortran 90.