Number

A small numeric composite for Composition-Oriented Programming. A Number wraps a Go int64 or float64 value and exposes its arithmetic as fallible operations that return a Result — so failures (the canonical example being a division by zero) are values, never panics and never nil.

This is the canonical Result use-case in the go-composites family:

quotient := numerator.Div(denominator)
if quotient.HasError() {
    fmt.Println(quotient.Error().Message()) // "division by zero"
} else {
    fmt.Println(quotient.Payload().(Number.Interface).ToGoString())
}

Number follows the org's Null-Object / never-nil invariant (enforced by the nonnil CI analyzer): the NullNumber variant in src/null satisfies the same Interface and reports IsNull() == true.

Install

export GOPRIVATE=github.com/go-composites GOPROXY=direct GOSUMDB=off
go get github.com/go-composites/number@main

Usage

[!NOTE] main.go

package main

import (
    "fmt"

    Number "github.com/go-composites/number/src"
)

func main() {
    six := Number.New(Number.WithInt(6))
    two := Number.New(Number.WithInt(2))
    zero := Number.New() // default zero (int)

    // Arithmetic returns a Result.
    sum := six.Add(two)
    fmt.Println(sum.Payload().(Number.Interface).ToGoString()) // 8

    // Division by zero is a value, not a panic.
    div := six.Div(zero)
    fmt.Println("has error:", div.HasError())      // true
    fmt.Println(div.Error().Message())             // division by zero

    // Comparisons return a go-composites/boolean.
    fmt.Println(six.GreaterThan(two).ToGoString()) // "true"
    fmt.Println(six.Inspect())                     // <Number:0x... kind=int value=6>
}

$ task build

API

Constructors

• New(opts ...Option) Interface — default integer zero.
• WithInt(int64) Option / WithFloat(float64) Option.
• null.New() Interface — the NullNumber Null-Object (IsNull() == true).

Conversions

• ToGoInt() int64, ToGoFloat() float64, ToGoString() string.
• IsInt() bool, IsFloat() bool, IsNull() bool.

Arithmetic (each returns Result.Interface)

• Add(other) Result / Sub(other) Result / Mul(other) Result — the result stays an integer only when both operands are integers, otherwise it is a float.
• Div(other) Result — a Result carrying Error.New("division by zero") when other is zero.
• Mod(other) Result — remainder (Go % for two integers, math.Mod otherwise); a Result carrying Error.New("modulo by zero") when other is zero.
• Abs() Result / Neg() Result — absolute value and negation, preserving the integer / float kind.

Comparisons (each returns Boolean.Interface)

• Equal(other) / LessThan(other) / GreaterThan(other).

Inspection

• Inspect() string — <Number:0x... kind=int value=...>.

License

BSD-3-Clause — see LICENSE.