NFun. Expressions Evaluator for .NET

To install NFun, run the following command in the Package Manager Console:

PM> Install-Package NFun 

What is the NFun?

This is an expression evaluator or a mini-script language for .net. It supports working with mathematical expressions as well as with collections, strings, hi-order functions and structures. NFun is quite similar to NCalc but with a rich type system and linq support. See the 'How to / specifications' section for details

Nfun can perform simple evaluations

  double d = Funny.Calc<double>(" 2 * 10 + 1 ") // 21  
  bool b   = Funny.Calc<bool>("false and (2 > 1)") // false

  // 'age' and 'name' are properties from input 'User' model 
  string userAlias = Funny.Calc<User,string> (
                       "if(age < 18) name else 'Mr. {name}' ", 
                        inputUser)  

as well as complex, with multiple composite inputs and outputs

  // Evaluate many values and set them into 'Person' object's properties 
  // inputs and outputs 'age', 'cars' and 'birthYear' are properties of 'Person' object 
  var personModel = new Person(birthYear: 2000);
  
  Funny.CalcContext(@"   
     age = 2022 - birthYear 
     cars = [
   	    { name = 'lada',   cost = 1200, power = 102 },
   	    { name = 'camaro', cost = 5000, power = 275 }
     ]
     ", personModel);
  
  Assert.Equal(22,   personModel.Age);
  Assert.Equal(2,    personModel.Cars.Count());
  Assert.Equal(1200, personModel.Cars[0].Cost);
  

Low-level hardcore API is also supported

  var runtime = Funny.Hardcore.Build("y = 2x+1");

  runtime["x"].Value = 42; //Write input data
  runtime.Run(); //Run script
  var result = runtime["y"].Value //collect results
  
  Console.WriteLine("Script contains these variables:"
  foreach(var variable in runtime.Variables)
     Console.WriteLine(
        "{variable.Name}:{variable.Type} {variable.IsOutput?"[OUTPUT]":"[INPUT]"}");

Key features

• Arithmetic, Bitwise, Discreet operators

  # Arithmetic operators: + - * / % // ** 
  y1 = 2*(x//2 + 1) / (x % 3 -1)**0.5 + 3x
  
  # Bitwise:     ~ | & ^ << >> 
  y2 = (x | y & 0xF0FF << 2) ^ 0x1234
	
  # Discreet:    and or not > >= < <= == !=
  y3 = x and false or not (y>0)

• If-expression

  simple  = if (x>0) x else if (x==0) 0 else -1
  complex = if (age>18)
                if (weight>100) 1
                if (weight>50)  2
                else 3
            if (age>16) 0
            else       -1     

• User functions and generic arithmetics

  sum3(a,b,c) = a+b+c
  
  r:real = sum3(1,2,3)
  i:int  = sum3(1,2,3)

• Array, string, numbers, structs and hi-order fun support

  out = {
    name = 'etaK'.reverse()
    values = [0xFF0F, 2_000_000, 0b100101]
    items = [1,2,3].map(rule 'item {it}')
  }

• Strict type system and type-inference algorithm

  y = 2x
  z:int = y*x
  m:real[] = [1,2,3].map(rule it/2)

• Double or decimal arithmetics
• Syntax and semantic customization
• Built-in functions
• Comments

How to

API - guide and examples

Syntax - guide and examples

Built in functions

---

Boring specification is better than no specification

Boring specification: Basics

Boring specification: Operators

Boring specification: Arrays

Boring specification: Texts (Strings)

Boring specification: Structs

Boring specification: Rules (Anonymous functions)

Boring specification: Types

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