I'm attempting to use CsvProvider for f# but it says the type isn't defined even though I'm importing FSharp.Data.
open FSharp.Data
type test = CsvProvider<"C:\\First_Names.csv">
I'm not using the interactive scripts. This is an .fs file. It doesn't tell me that FSharp.Data can't be found. It was even in the intellisense.
What are some ways I can diagnose this problem, because I'm at a loss now.
This is probably due to the fact that you either having FSharp.Data.SqlClient referenced or FSharp.Data.TypeProviders (from the F#3 distribution). Both use that namespace hierarchy.
This is the same as how namespaces work in C# or VB .NET.
Related
Why I cannot create Type Provider as *.exe file with [<TypeProviderAssembly()>] and [<EntryPoint>] inside?
When I try to reference such TP using #r #"d:\TP\bin\Debug\MyTypeProvider.exe", I see the following:
test.fsx(3,1): error FS3031: The type provider 'd:\TP\bin\Debug\MyTypeProvider.exe' reported an error: Assembly attribute 'TypeProviderAssemblyAttribute' refers to a designer assembly 'MyTypeProvider' which cannot be loaded or doesn't exist. Could not load file or assembly 'file:///d:\TP\bin\Debug\MyTypeProvider.dll' or one of its dependencies. The system cannot find the file specified.
I need to have a type inference runtime in separate process, because it should be 64bit (unlike 32bit VS process). But I want to pack all things into one file, reference it from VS and start as external process.
Perhaps there's some good underlying reason for always looking for DLLs instead of EXEs, but I suspect this may be an arbitrary limitation.
I can get things to work in FSI if I supply the assembly's full name to the TypeProviderAssemblyAttribute constructor (e.g. [<TypeProviderAssembly("MyExe, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null")>]), but IntelliSense doesn't work and I can't use the TP from other projects. Consider filing a bug with the team - but it would probably help if you could justify why you need an EXE instead of a DLL for your scenario.
I've used F# to do some quick data-analysis using datastructures from another project. To do so, it needs access to this project; i.e. it needs an assembly reference - but the project is an executable.
I've tried this in F# interactive, and it almost works*; I can #I the appropriate path and #r the executable and a few support dll's - but I can't actually use em. And whatever I do, I can't get the reference into a compiled F# program: VS lets me add a reference just fine, and the appropriate compiler option -r:X:full\path\here.exe is correctly generated by the project, but none of the datastructures are present and the compiler complains of non-existent namespaces; it's as if the reference didn't exist. The application is 64-bit, which may be relevant. 64-bit dll's work fine.
(*) after setting fsi.exe to run in 64-bit mode it thinks it can load it, but actually using it returns FS0193: internal error.
How can I reference a managed 64-bit executable from an F# project?
To others with this same issue: as a workaround, I'm now compiling the executable as Any CPU (which will be executed in 64-bit mode, so behaves the same). This allows FSI and the compiler to reference it. Based on the questions referenced in the comments, this seems to be a known bug that will hopefully be fixed some day.
I am creating my type in FSX and passing those types into the Razor templating engine with the open source RazorEngine project.
Hosting Razor outside of ASP.NET requires compiling the Razor templates. If I pass a model created in FSX into the template, will System.CodeDom be able to have access to that type created by FSI? The basic error that I get is "The type or namespace name 'FSI_0004' could not be found".
Code that's compiled using System.CodeDom cannot generally have access to the code loaded in F# Interactive - the CodeDom essentially writes the C#/F# source code to disk and then invokes the command line compiler on the code (and the command line compiler cannot reference code loaded in F# Interactive).
There may be a way to get it working though - You could use the F# CodeDom provider from PowerPack. You could modify it to generate the source code (as it currently does) and then send the generated code to F# Interactive (instead of invoking command line compiler). This way, the code compiled on-the-fly could see F# Interactive code.
There are some issues that need to be resolved
Is it possible to provide your own CodeDom provider to RazorEngine?
The F# CodeDom provider may not correctly handle code generated by Razor (so you may need to fix/workaround a few things in the F# CodeDom provider). You may also need to modify it to generate code that works nicely with F# interactive (e.g. remove top-level namespaces)
What instance of F# Interactive do you want to use? (And how to get standard input, so that you can send your code there)
Do you need to load the compiled assembly and pass it back to Razor? I'm not sure if this can be done with F# Interactive.
These all depend on your scenario - but I guess that it may be possible to get what you want (possibly with some workarounds).
Is there a way within FSI that I can reference and use registered COM components?
In a normal .fs compiled program I can simply reference the component in question and then open the relevant generated namespace(s). In a .fsx file, however, I can't seem to replicate this behaviour. I have tried using #r to reference the .dll directly, and I have tried using #I to point to the directory followed #r both with the library's "friendly" name and the file name, but nothing seems to work.
Are you only able to reference .NET assemblies from a .fsx? I don't really want to have to write/gen a wrapper assembly. I am hoping there might be a way to force FSI to take whatever steps the normal executable takes in order to provide the interop layer.
When you add a reference to a COM component in Visual Studio, it invokes a tool to generate a wrapper (standard .NET assembly) and then references the wrapper.
If you want to reference COM from fsx, you'll need to generate the wrapper yourself (or find the one generated by Visual Studio?) The tool that generates the wrapper that is called TlbImp.exe (see Type Library Importer on MSDN).
I'm trying to use the Seq.generate_using function but unfortunately, I don't seem to be able to find it. I thought it would be living here:
Microsoft.FSharp.Collections.Seq.generate_using
But it doesn't. I am getting the error listed below.
C:\Users\Owner\Documents\Visual Studio
2008\Projects\fsharp1\Program.fs(54,63):
error FS0039: The value, constructor,
namespace or type 'generate_using' is
not defined. A construct with this
name was found in
FSharp.PowerPack.dll, which contains
some modules and types that were
implicitly referenced in some previous
versions of F#. You may need to add an
explicit reference to this DLL in
order to compile this code.
According to the Sept 2008 CTP Release Notes:
The F# library is split into two
components. FSharp.Core.dll: Contains
the core F# libraries, which will be
stabilized and versioned infrequently.
FSharp.PowerPack.dll: Contains
additional useful F# libraries and
tools which will version more
frequently, and allow continued
innovation on top of the core F#
language and libraries.
Some methods in the Seq module were moved into the FSharp.PowerPack assembly, so you can only get those methods by doing the following:
If you're using Visual Studio, open your Solution Explorer, right-click on the project file, choose "Add Reference", and add "FSharp.PowerPack.dll".
If you're using a script file or fsi, then type #r "FSharp.PowerPack";; to load the assembly.
Now you should be able to call Seq.generate_using.
The #r "FSharp.PowerPack";; works for me but the addition of PowerPack to my solution does not. I am trying to use HashSet<>.