From 7b09445140983623173203c4594bb54dcd55fe1e Mon Sep 17 00:00:00 2001
From: Marius Peter <dev@marius-peter.com>
Date: Thu, 13 Nov 2025 16:15:05 +0100
Subject: Add nutrient-value-pair/c contract.

---
 models/nutrient.rkt | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

(limited to 'models')

diff --git a/models/nutrient.rkt b/models/nutrient.rkt
index 10e274e..944583e 100644
--- a/models/nutrient.rkt
+++ b/models/nutrient.rkt
@@ -1,12 +1,14 @@
 #lang racket
 
 (provide
- ;; Struct definitions
+ ;; Model struct
  nutrient
  nutrient?
  nutrient-id nutrient-name nutrient-formula
- ;; SQL CRUD
+ ;; Contracts
+ nutrient-value-pair/c
  (contract-out
+  ;; SQL CRUD
   [create-nutrient! (-> string? string? nutrient?)]
   [get-nutrients (-> (listof nutrient?))]
   [get-nutrient (->* ()
@@ -33,6 +35,9 @@
              (nutrient-id v)
              (nutrient-name v))))
 
+(define nutrient-value-pair/c
+  (cons/c nutrient? (and/c real? (>=/c 0))))
+
 
 ;; CREATE
 
-- 
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