lemma-engine 0.9.5

A pure, declarative language for business rules.
Documentation 
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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