spec recipe_scaling
"""
Recipe Scaling

Demonstrates calculations and scaling.
Measure a recipe up or down based on servings needed.
"""

uses lemma units

data temperature: measure
  -> unit celsius: 1.0

data recipe: text
  -> option "chocolate_cake"
  -> option "bread"
  -> option "cookies"

data butter_needed: 0.5
data eggs_needed:   3
data flour_needed:  2
data sugar_needed:  1.5
data recipe_name:   recipe
data desired_servings: number
  -> minimum 1

data original_servings: number
  -> minimum 1

rule scaling_factor:
  desired_servings / original_servings

rule scaled_flour:
  flour_needed * scaling_factor

rule scaled_sugar:
  sugar_needed * scaling_factor

rule scaled_butter:
  butter_needed * scaling_factor

rule scaled_eggs:
  eggs_needed * scaling_factor

rule total_dry_ingredients:
  scaled_flour + scaled_sugar

rule baking_time:
  30 minute
  unless desired_servings <= 4 then 35 minute
  unless desired_servings >= 8 then 40 minute

rule oven_temperature:
  175 celsius
  unless recipe_name is "bread" then 190 celsius