Branded Types

The GalaSwap SDK uses TypeScript branded types to prevent common mistakes when working with prices and amounts. These types help avoid, for example, mixing up regular prices with square root prices, which can lead to calculation errors.

What are Branded Types?

Branded types are a TypeScript pattern that adds compile-time safety by "branding" primitive types with additional metadata. This prevents you from accidentally passing the wrong type of value to a function.

Available Branded Types

Price Types

Type	Description	Usage
PriceIn	Input price values (can be string, number, or BigNumber)	When providing price parameters to functions
Price	Calculated price values (always BigNumber)	When receiving price results from calculations
SqrtPriceIn	Input square root price values (can be string, number, or BigNumber)	When providing square root price parameters
SqrtPrice	Calculated square root price values (always BigNumber)	When receiving square root price results

Usage Example

Casting

Consider a function that requires a PriceIn type argument. We can pass in a string, number, or BigNumber, but only after casting it to PriceIn:

function myFunction(price: PriceIn) {
  // ...
}

myFunction(0.5 as PriceIn);
myFunction('0.5' as PriceIn);
myFunction(BigNumber(0.5) as PriceIn);

myFunction(0.5); // ERROR!

The point of forcing this casting is to require the caller to declare explicitly that they are passing in a price value (as opposed to a square root price value, or some other numeric value) thus helping to prevent incorrect data being used.