I just installed Visual Studio Code on a different laptop and then proceeded to get the Ionide-fsharp extension. I then tried to run this simple piece of code:
open System
let rec factorial n =
if n = 0
then 1
else n * factorial (n - 1)
factorial 5
But then I get this error and I can't seem to fix it:
open: the term 'open' is not recognized as the name of a cmdlet,
function, script file, or operable program. Check the spelling on the name,
of if a path was included, verify that the path is correct and try again.
It then proceeds to throw a bunch more nonsense at me and repeats the error above for every single line of code I have written afterwards. Please help.
Related
a=1
% Construct the trasfer function
num=[a 1 3]
den=[1 2 10]
G=tf(num,den)
% Impulse response
impulse(G)
% Step response
step(G)
When I click on 'run' this error appears "error: Order numerator >= order denominator"
If you follow the error on the terminal, it suggests that line 95 in imp_invar.m of the control package is to blame. (if you don't know where this was installed, you can find out by typing pkg list in your terminal)
If you convert this error to a warning, the code continues. Obviously you do so at your own risk. I would make a backup of the original .m file just in case.
Note that the same code run on matlab does not issue any error or warning (which is odd in itself, given the stark note about invalid impulse invariance in this scenario from octave ... there is a reference quoted inside imp_invar.m if you're interested.)
I am trying to improve my loop computation speed by using foreach, but there is a simple Rcpp function I defined inside of this loop. I saved the Rcpp function as mproduct.cpp, and I call out the function simply using
sourceCpp("mproduct.cpp")
and the Rcpp function is a simple one, which is to perform matrix product in C++:
// [[Rcpp::depends(RcppArmadillo, RcppEigen)]]
#include <RcppArmadillo.h>
#include <RcppEigen.h>
// [[Rcpp::export]]
SEXP MP(const Eigen::Map<Eigen::MatrixXd> A, Eigen::Map<Eigen::MatrixXd> B){
Eigen::MatrixXd C = A * B;
return Rcpp::wrap(C);
}
So, the function in the Rcpp file is MP, referring to matrix product. I need to perform the following foreach loop (I have simplified the code for illustration):
foreach(j=1:n, .package='Rcpp',.noexport= c("mproduct.cpp"),.combine=rbind)%dopar%{
n=1000000
A<-matrix(rnorm(n,1000,1000))
B<-matrix(rnorm(n,1000,1000))
S<-MP(A,B)
return(S)
}
Since the size of matrix A and B are large, it is why I want to use foreach to alleviate the computational cost.
However, the above code does not work, since it provides me error message:
task 1 failed - "NULL value passed as symbol address"
The reason I added .noexport= c("mproduct.cpp") is to follow some suggestions from people who solved similar issues (Can't run Rcpp function in foreach - "NULL value passed as symbol address"). But somehow this does not solve my issue.
So I tried to install my Rcpp function as a library. I used the following code:
Rcpp.package.skeleton('mp',cpp_files = "<my working directory>")
but it returns me a warning message:
The following packages are referenced using Rcpp::depends attributes however are not listed in the Depends, Imports or LinkingTo fields of the package DESCRIPTION file: RcppArmadillo, RcppEigen
so when I tried to install my package using
install.packages("<my working directory>",repos = NULL,type='source')
I got the warning message:
Error in untar2(tarfile, files, list, exdir, restore_times) :
incomplete block on file
In R CMD INSTALL
Warning in install.packages :
installation of package ‘C:/Users/Lenovo/Documents/mproduct.cpp’ had non-zero exit status
So can someone help me out how to solve 1) using foreach with Rcpp function MP, or 2) install the Rcpp file as a package?
Thank you all very much.
The first step would be making sure that you are optimizing the right thing. For me, this would not be the case as this simple benchmark shows:
set.seed(42)
n <- 1000
A<-matrix(rnorm(n*n), n, n)
B<-matrix(rnorm(n*n), n, n)
MP <- Rcpp::cppFunction("SEXP MP(const Eigen::Map<Eigen::MatrixXd> A, Eigen::Map<Eigen::MatrixXd> B){
Eigen::MatrixXd C = A * B;
return Rcpp::wrap(C);
}", depends = "RcppEigen")
bench::mark(MP(A, B), A %*% B)[1:5]
#> # A tibble: 2 x 5
#> expression min median `itr/sec` mem_alloc
#> <bch:expr> <bch:tm> <bch:tm> <dbl> <bch:byt>
#> 1 MP(A, B) 277.8ms 278ms 3.60 7.63MB
#> 2 A %*% B 37.4ms 39ms 22.8 7.63MB
So for me the matrix product via %*% is several times faster than the one via RcppEigen. However, I am using Linux with OpenBLAS for matrix operations while you are on Windows, which often means reference BLAS for matrix operations. It might be that RcppEigen is faster on your system. I am not sure how difficult it is for Windows user to get a faster BLAS implementation (https://csgillespie.github.io/efficientR/set-up.html#blas-and-alternative-r-interpreters might contain some pointers), but I would suggest spending some time on investigating this.
Now if you come to the conclusion that you do need RcppEigen or RcppArmadillo in your code and want to put that code into a package, you can do the following. Instead of Rcpp::Rcpp.package.skeleton() use RcppEigen::RcppEigen.package.skeleton() or RcppArmadillo::RcppArmadillo.package.skeleton() to create a starting point for a package based on RcppEigen or RcppArmadillo, respectively.
If I declare a function
test(A) -> 3.
Erlang generates a warning about variable A not being used. However the definition
isEqual(X,X) -> 1.
Doesn't produce any warning but
isEqual(X,X) -> 1;
isEqual(X,Y) -> 0.
again produces a warning but only for the second line.
The reason why that doesn't generate a warning is because in the second case you are asserting (through pattern matching), by using the same variable name, that the first and second arguments to isEqual/2 have the same value. So you are actually using the value of the argument.
It might help to understand better if we look at the Core Erlang code produced from is_equal/2. You can get .core source files by compiling your .erl file in the following way: erlc +to_core pattern.erl (see here for pattern.erl).
This will produce a pattern.core file that will look something like this (module_info/[0,1] functions removed):
module 'pattern' ['is_equal'/2]
attributes []
'is_equal'/2 = fun (_cor1,_cor0) ->
case <_cor1,_cor0> of
%% Line 5
<X,_cor4> when call 'erlang':'=:=' (_cor4, X) ->
1
%% Line 6
<X,Y> when 'true' ->
0
end
As you can see, each function clause from is_equal/2 in the .erl source code gets translated to a case clause in Core Erlang. X does get used in the first clause since it needs to be compared to the other argument. On the other hand neither X or Y are used in the second clause.
I'm using luacheck (within the Atom editor), but open to other static analysis tools.
Is there a way to check that I'm using an uninitialized table field? I read the docs (http://luacheck.readthedocs.io/en/stable/index.html) but maybe I missed how to do this?
In all three cases in the code below I'm trying to detect that I'm (erroneously) using field 'y1'. None of them do. (At run-time it is detected, but I'm trying to catch it before run-time).
local a = {}
a.x = 10
a.y = 20
print(a.x + a.y1) -- no warning about uninitialized field y1 !?
-- luacheck: globals b
b = {}
b.x = 10
b.y = 20
print(b.x + b.y1) -- no warning about uninitialized field y1 !?
-- No inline option for luacheck re: 'c', so plenty of complaints
-- about "non-standard global variable 'c'."
c = {} -- warning about setting
c.x = 10 -- warning about mutating
c.y = 20 -- " " "
print(c.x + c.y1) -- more warnings (but NOT about field y1)
The point is this: as projects grow (files grow, and the number & size of modules grow), it would be nice to prevent simple errors like this from creeping in.
Thanks.
lua-inspect should be able to detect and report these instances. I have it integrated into ZeroBrane Studio IDE and when running with the deep analysis it reports the following on this fragment:
unknown-field.lua:4: first use of unknown field 'y1' in 'a'
unknown-field.lua:7: first assignment to global variable 'b'
unknown-field.lua:10: first use of unknown field 'y1' in 'b'
unknown-field.lua:14: first assignment to global variable 'c'
unknown-field.lua:17: first use of unknown field 'y1' in 'c'
(Note that the integration code only reports first instances of these errors to minimize the number of instances reported; I also fixed an issue that only reported first unknown instance of a field, so you may want to use the latest code from the repository.)
People who look into questions related to "Lua static analysis" may also be interested in the various dialects of typed Lua, for example:
Typed Lua
Titan
Pallene
Ravi
But you may not have heard of "Teal". (early in its life it was called "tl"); .
I'm taking the liberty to answer my original question using Teal, since I find it intriguing.
-- 'record' (like a 'struct')
local Point = record
x : number
y : number
end
local a : Point = {}
a.x = 10
a.y = 20
print(a.x + a.y1) -- will trigger an error
-- (in VS Code using teal extension & at command line)
From command line:
> tl check myfile.tl
========================================
1 error:
myfile.tl:44:13: invalid key 'y1' in record 'a'
By the way...
> tl gen myfile.tl'
creates a pure Lua file: 'myfile.lua' that has no type information in it. Note: running this Lua file will trigger the 'nil' error... lua: myfile.lua:42: attempt to index a nil value (local 'a').
So, Teal gives you a chance to catch 'type' errors, but it doesn't require you to fix them before generating Lua files.
UPDATE:
I now realize that the question was stupid, I should have just filed the issue. In hindsight, I don't see why I even asked this question.
The issue is here: https://github.com/fsharp/FSharp.Compiler.Service/issues/544
Original question:
I'm using FSharp Compiler Services for parsing some F# code.
The particular piece of code that I'm facing right now is this:
let f x y = x+y
let g = f 1
let h = (g 2) + 3
This program yields a TAST without the (+) call on the last line. That is, the compiler service returns TAST as if the last line was just let h = g 2.
The question is: is this is a legitimate bug that I ought to report or am I missing something?
Some notes
Here is a repo containing minimal repro (I didn't want to include it in this question, because Compiler Services require quite a bit of dancing around).
Adding more statements after the let h line does not change the outcome.
When compiled to IL (as opposed to parsed with Compiler Services), it seems to work as expected (e.g. see fiddle)
If I make g a value, the program parses correctly.
If I make g a normal function (rather than partially applied one), the program parses correctly.
I have no priori experience with FSharp.Compiler.Services but nevertheless I did a small investigation using Visual Studio's debugger. I analyzed abstract syntax tree of following string:
"""
module X
let f x y = x+y
let g = f 1
let h = (g 2) + 3
"""
I've found out that there's following object inside it:
App (Val (op_Addition,NormalValUse,D:\file.fs (6,32--6,33) IsSynthetic=false),TType_forall ([T1; T2; T3],TType_fun (TType_var T1,TType_fun (...,...))),...,...,...)
As you can see, there's an addition in 6th line between characters 32 and 33.
The most likely explanation why F# Interactive doesn't display it properly is a bug in a library (maybe AST is in an inconsistent state or pretty-printing is broken). I think that you should file a bug in project's issue tracker.
UPDATE:
Aforementioned object can be obtained in a debbuger in a following way:
error.[0]
(option of Microsoft.FSharp.Compiler.SourceCodeServices.FSharpImplementationFileDeclaration.Entity)
.Item2
.[2]
(option of Microsoft.FSharp.Compiler.SourceCodeServices.FSharpImplementationFileDeclaration.MemberOrFunctionOrValue)
.Item3
.f (private member)
.Value
(option of Microsoft.FSharp.Compiler.SourceCodeServices.FSharpExprConvert.ConvExprOnDemand#903)
.expr