Agent skill
clojure-guardrails
Reference for Guardrails library with Malli in Clojure. Use when working with `>defn`, `>defn-`, `>def`, `>fdef` macros, gspec syntax, or function validation. Triggers on guardrails imports, `com.fulcrologic.guardrails.malli`, function specs with `=>` operator, or questions about runtime validation in Clojure.
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npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/data/clojure-guardrails
SKILL.md
Clojure Guardrails (Malli)
Detection
Check if guardrails is in use:
bash
grep -r "guardrails.enabled" deps.edn shadow-cljs.edn 2>/dev/null
Setup
deps.edn:
clojure
{:deps {com.fulcrologic/guardrails {:mvn/version "1.2.16"}
metosin/malli {:mvn/version "0.20.0"}}
:aliases {:dev {:jvm-opts ["-Dguardrails.enabled=true"]}}}
See https://clojars.org/com.fulcrologic/guardrails for the latest version.
Enable at runtime: -Dguardrails.enabled=true
Import
clojure
(require '[com.fulcrologic.guardrails.malli.core :refer [>defn >defn- >def >fdef | ? =>]])
Core Macros
| Macro | Purpose |
|---|---|
>defn |
Define function with inline spec |
>defn- |
Private function with spec |
>def |
Register malli schema |
>fdef |
Declare spec without body |
? |
Nilable shorthand [:maybe schema] |
| |
"Such that" constraints |
=> |
Separates args from return |
Gspec Syntax
[arg-specs* (| arg-preds+)? => ret-spec (| ret-preds+)?]
Basic:
clojure
(>defn add [a b]
[:int :int => :int]
(+ a b))
With constraints:
clojure
(>defn ranged-rand [start end]
[:int :int | #(< start end)
=> :int | #(>= % start) #(< % end)]
(+ start (long (rand (- end start)))))
Nilable:
clojure
(>defn find-user [id]
[:int => (? :map)]
(get users id))
Multi-arity:
clojure
(>defn greet
([name]
[:string => :string]
(str "Hello, " name))
([greeting name]
[:string :string => :string]
(str greeting ", " name)))
Variadic:
clojure
(>defn sum [x & more]
[:int [:* :int] => :int]
(apply + x more))
Map schemas:
clojure
(>defn process-user [user]
[[:map [:name :string] [:age :int]] => :string]
(str (:name user) " is " (:age user)))
Schema Registry
This is an optional feature.
clojure
(require '[com.fulcrologic.guardrails.malli.registry :as gr.reg])
;; Register schemas
(>def :user/name :string)
(>def :user/age :int)
(>def :user/record [:map :user/name :user/age])
;; Use in functions
(>defn get-user [id]
[:int => (? :user/record)]
(lookup id))
Detailed Reference
See gspec-syntax.md for complete syntax documentation.
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