Numbers

Ghost has a single numberic type; arbitrary-precision fixed-point decimals. While most other languages contain representations for integers, floats, doubles, etc., we found that having just a single number type was easier to use even at the slight cost of performance.

Because Ghost uses an arbitrary-precision fixed-point decimal system, it is extremely accurate. Number values look like you expect from other languages:

0
1234
-5678
0.001
3.14159
12.34
-1.76

Precision

Float point numbers (or any binary floating point type) can't represent fractional decimals (0.1) precisely. When adding and subtracting them repeatedly will cause rounding errors.

For example, let's consider this code in Go:

package main

import "fmt"

func main() {
    var n float64 = 0

    for i := 0; i < 1000; i++ {
        n += .01
    }

    fmt.Println(n)
}

You might expect it to print 10, but it in fact prints 9.999999999999831. This may not be so much of an issue, but if you were having to calculate with extreme precision (such as money), you could find yourself short a few dollars in some extreme cases.

If you were to run the same program above in Ghost, you'd find that the result does come out to exactly 10:

value = 0

for (i = 0; i < 1000; i = i + 1) {
    value = value + 0.01
}

print(value)

// expected value: 10

Numbers in Ghost can only represent numbers with a maximum of 2^31 digits after the decimal point.

Scientific Notation

Numeric values can be represented in scientific notation by using e. This returns a value multiplied by the specified power of 10.

1.1    // expected value: 1.1
1.1e0  // expected value: 1.1
1.1e1  // expected value: 11.0
1.1e2  // expected value: 110.0
1.1e3  // expected value: 1100.0
8e-2   // expected value: 0.08

Methods

round()

The round() method rounds the given number to the nearest integer to the specified precision.

value = 123.4.round()

// expected value: 123

value = 123.456.round(1)

// expected value: 123.5

toString()

The toString() method returns the given number as a string.

value = 3.141592.toString()

// expected value: "3.141592"