What is “point free” style (in Functional Programming)?

Question

A phrase that I\'ve noticed recently is the concept of \"point free\" style...

First, there was this question, and also this one.

Then, I discovered here the

Answer 1

Here is one example in TypeScript without any other library:

interface Transaction {
  amount: number;
}

class Test {
  public getPositiveNumbers(transactions: Transaction[]) {
    return transactions.filter(this.isPositive);

    //return transactions.filter((transaction: {amount: number} => transaction.amount > 0));
  }

  public getBigNumbers(transactions: Transaction[]) {
    // point-free
    return transactions.filter(this.moreThan(10));

    // not point-free
    // return transactions.filter((transaction: any) => transaction.amount > 10);
  }

  private isPositive(transaction: Transaction) {
    return transactions.amount > 0;
  }

  private moreThan(amount: number) {
    return (transaction: Transaction) => {
      return transactions.amount > amount;
    }
  }
}

You can see point-free style is more "fluent" and easier to read.