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subtract (Function)

The subtract function subtracts the second number from the first and returns the result. It handles null values gracefully and automatically converts floating-point results to integers when they represent whole numbers, providing clean and predictable numeric operations.

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Note

This provider is currently in POC (proof-of-concept) status and under active development. Features and APIs may change without notice. Not intended for production infrastructure.

Like the add function, subtract optimizes result types to ensure that whole numbers are returned as integers rather than floats. This makes configurations more readable and prevents unnecessary decimal notation in outputs and resource calculations.

Capabilities

This function enables you to:

  • Arithmetic calculations: Perform basic subtraction in Terraform configurations
  • Counter decrements: Subtract values from existing counters or totals
  • Resource calculations: Compute remaining capacity or available resources
  • Delta calculations: Calculate differences between baseline and current values
  • Budget calculations: Determine remaining budget or cost differences

Example Usage

locals {
  example_result = sum(
    # Function arguments here
  )
}

output "function_result" {
  description = "Result of sum function"
  value       = local.example_result
}

Signature

subtract(a, b)

Arguments

Return Value

Returns the difference as a number. The return type is automatically optimized: - If the result is a whole number, returns an integer - If the result has decimal places, returns a float - Returns null if either input is null

Common Patterns

Remaining Capacity Calculation

variable "total_capacity" {
  default = 100
}

variable "current_usage" {
  default = 35
}

locals {
  remaining_capacity = provider::pyvider::subtract(var.total_capacity, var.current_usage)  # 65
}

Budget Remaining

variable "budget_allocated" {
  default = 5000.00
}

variable "budget_spent" {
  default = 3250.75
}

locals {
  budget_remaining = provider::pyvider::subtract(var.budget_allocated, var.budget_spent)  # 1749.25
}

Documentation version: 0.0.19 | Last updated: 2025-11-09