Shelve

Research implementation of reactive calculations with declarative defined functional models.

This is my graduate work focused on learning how to implement a hypothetical translator of mathematical expressions with some useful capabilities to work with functional models.

Capabilities

• Assign one or more expressions to a variable.
• Combine variables into models.
• Merge models into each other to make variables depend on corresponded expressions in both.
• All expressions are reactive.
• All expressions are lazy, cached and support change propagation.
• All values are 8-byte floating point numbers.
• All values are stateless. Except iterators.

Example

Define models like:

{
  "Name" : "Knight"
  "Expressions" :
  [
    "Power = 5",
    "Damage = 0",
    "CriticalDamage = Power * Damage"
  ]
},

{
  "Name" : "Sword",
  "Uses" : ["Knight"],
  "Expressions" :
  {
    "Power += 5",
    "Damage += 1 + 1.25 * Power"
  }
}

{
  "Name" : "Shield",
  "Uses" : "Knight",
  "Expressions" :
  [
    "Power -= 5",
  ]
}

Use from code:

var knight = VariableSet.GetInstance("Knight");
var sword = VariableSet.GetInstance("Sword");
var shield = VariableSet.GetInstance("Shield");

knight.Merge(sword).Merge(shield);
var criticalDamage = knight["CriticalDamage"]; // 36.25

Iterators

Iterators are stateful values.

"it = [0, it + 1]"

Where:

• 0 - start value
• it + 1 - expression to calculate the next value.

Iterator store last calculated value and recalculate it on MoveNextValue() call.

More interesting example

{
  "Name" : "Fibonacci"
  "Expressions":
  {
    "f1 = [0, f2]",
    "f2 = [1, f3]",
    "f3 = [1, t1 + t2]"
  }
}

var fibonacci = VariableSet.Get("Fibonacci");
Debug.Log(fibonacci["f1"]); // 0
Debug.Log(fibonacci["f2"]); // 1
Debug.Log(fibonacci["f3"]); // 1

var f1 = fibonacci.Get<Iterator>("f1");
var f2 = fibonacci.Get<Iterator>("f2");
var f3 = fibonacci.Get<Iterator>("f3");

f1.MoveNextValue();
f2.MoveNextValue();
f3.MoveNextValue();

Debug.Log(fibonacci["f1"]); // 1
Debug.Log(fibonacci["f2"]); // 1
Debug.Log(fibonacci["f3"]); // 2

f1.MoveNextValue();
f2.MoveNextValue();
f3.MoveNextValue();

Debug.Log(fibonacci["t1"]); // 1
Debug.Log(fibonacci["t2"]); // 2
Debug.Log(fibonacci["t"]);  // 3

f1.MoveNextValue();
f2.MoveNextValue();
f3.MoveNextValue();

Debug.Log(fibonacci["t1"]); // 2
Debug.Log(fibonacci["t2"]); // 3
Debug.Log(fibonacci["t"]);  // 5

// ...

Functions

Supports all System.Math functions for double floating point numbers. Just make a call in lowercase.

"sin = sin(x)"
"angle = atan2(x, y)"