valid.clj

(ns fun.matching 
  (:require [clojure.core.match :refer [match emit-pattern to-source groupable?]]))

;; adding set literals to match
(defrecord SetPattern [set])
(defmethod emit-pattern clojure.lang.PersistentHashSet
  [pat]
  (SetPattern. pat))

(defmethod groupable? [SetPattern SetPattern]
  [a b]
  (let [a (:set a)
        b (:set b)]
    (= a b)))

(defmethod to-source SetPattern
  [pat ocr]
  `(contains? ~(:set pat) ~ocr))

;; This allows 
(match [[1 2 "green"]]
  [[1 _ "blue"]] :a0
  [[_ 2 #{"green" "blue"}]] :a1) ; => :a1

;; I'd like to add e.g. 
(match [[1 2 "green"]]
  [[1 _ #(= % "green")]] :a0
  [[_ 2 #{"green" "blue"}]] :a1) ; => :a0
  
;; But the below won't work
(defrecord FunctionPattern [fn])
(defmethod emit-pattern clojure.lang.IFn
  [pat]
  (FunctionPattern. pat))

(defmethod to-source FunctionPattern
  [pat ocr]
  `(~(:fn pat) ~ocr))