Getting Started

Installation

You can install the package by adding this reference to the .csproj:

<PackageReference Include="JustFunctional.Core" Version="2.0.2" />

or by using this command in the console:

dotnet add package JustFunctional.Core --version 2.0.2

You can find the package in nuget here for more details.

Usage

Evaluate a function directly

You can start evaluating with the default configuration using the Function class:

string fx = "(X*4)^2";
Function f = new Function(fx);
decimal result =  f.Evaluate(new EvaluationContext(new Dictionary<string, decimal>() { ["X"] = 3 }));
//result = 144

or evaluate an constant expression like this:

string fx = "(3*4)^2";
Function f = new Function(fx);
decimal result = f.Evaluate(new EvaluationContext());
//result = 144

Using an IoC Container

If you are using an IoC Container we recommend to use the IFunctionFactory and that way all of your Function instances will share the same configuration:

1- Create and extension method:

using Microsoft.Extensions.Hosting;
public static class JustFunctionalExtensions
{
    
    public static IServiceCollection AddJustFunctional(this IServiceCollection services)
    {
        var factory = FunctionFactoryBuilder.ConfigureFactory(options =>
        {
            options
                .WithEvaluationContextVariablesProvider()
                .WithDefaultsTokenProvider()
                .WithCompiledEvaluator();
        });
        services.AddSingleton<IFunctionFactory>(factory);
        return services;
    }
}

2- Register the factory with the IoC Container:

public void ConfigureServices(IServiceCollection services)
{
    ...
    services.AddJustFunctional();
    ...
}

3- Use in a controller or in any other place:

using JustFunctional.Core;
[ApiController()]
[Route("api/maths")]
public class MathController : ControllerBase
{
    private readonly IFunctionFactory _functionFactory;

    public MathController(IFunctionFactory functionFactory)
    {
        _functionFactory = functionFactory;
    }

    [HttpGet("evaluate")]
    public async Task<decimal> Evaluate([FromQuery] decimal x)
    {
        string fx = "(X*4)^2";
        Function f = _functionFactory.Create(fx);
        return await f.EvaluateAsync(new EvaluationContext(new Dictionary<string, decimal>() {["X"] = x}));
    }
}

Note that EvaluateAsync supports Parallel calls without any Issue.

Validate if an expression is syntactically correct

You can use the TryCreate before evaluating a given function to make sure the expression is correct

[HttpGet("is-valid")]
public  TryCreateFunctionResult IsValid([FromQuery] string fx)
{
    var allowedVariables = new PredefinedVariablesProvider("X");
    TryCreateFunctionResult result = _functionFactory.TryCreate(fx,allowedVariables);
    return result;
}

What’s next

You can learn the more about in the Try It Out or go to the docs.