How do I take text-string, that is supposed to be F#-code, and parse it into F#-code, to print out the results on the screen?
I'm guessing it would be solved through a feature in .NET, so it can be done through F# itself or C#.
In what way is this probably solved on tryfsharp.org?
The desired can be achieved using F# CodeDom provider. A minimal runnable snippet below demonstrates the required steps. It takes an arbitrary presumably correct F# code from a string and tries to compile it into an assembly file. If successful, then it loads this just synthesized assembly from the dll file and invokes a known function from there, otherwise it shows what's the problem with compiling the code.
open System
open System.CodeDom.Compiler
open Microsoft.FSharp.Compiler.CodeDom
// Our (very simple) code string consisting of just one function: unit -> string
let codeString =
"module Synthetic.Code\n let syntheticFunction() = \"I've been compiled on the fly!\""
// Assembly path to keep compiled code
let synthAssemblyPath = "synthetic.dll"
let CompileFSharpCode(codeString, synthAssemblyPath) =
use provider = new FSharpCodeProvider()
let options = CompilerParameters([||], synthAssemblyPath)
let result = provider.CompileAssemblyFromSource( options, [|codeString|] )
// If we missed anything, let compiler show us what's the problem
if result.Errors.Count <> 0 then
for i = 0 to result.Errors.Count - 1 do
printfn "%A" (result.Errors.Item(i).ErrorText)
result.Errors.Count = 0
if CompileFSharpCode(codeString, synthAssemblyPath) then
let synthAssembly = Reflection.Assembly.LoadFrom(synthAssemblyPath)
let synthMethod = synthAssembly.GetType("Synthetic.Code").GetMethod("syntheticFunction")
printfn "Success: %A" (synthMethod.Invoke(null, null))
else
failwith "Compilation failed"
Being fired-up it produces the expected output
Success: "I've been compiled on the fly!"
If you gonna play with the snippet it requires referencing FSharp.Compiler.dll and FSharp.Compiler.CodeDom.dll. Enjoy!
I'm guessing it would be solved through a feature in .NET, so it can be done through F# itself or C#.
Nope. F# provides comparatively tame metaprogramming facilities. You'll need to rip the relevant code out of the F# compiler itself.
F# has an interpreter fsi.exe which can do that you want. I think it also has some API.
