• Easy to imagine behavior

• Minimum to remember

  • All usage and examples are documented in docstring

(require '[merr.core :as merr])
;; => nil
;; for ClojureScript
;; (require '[merr.core :as merr :include-macros true])
(merr/let +err+ [foo 1
                 bar (merr/error)
                 baz (* bar 2)]
  {:+err+ +err+ :foo foo :bar bar :baz baz})
;; => {:+err+ (merr/error), :foo 1, :bar nil, :baz nil}

error record

(defrecord MerrError [type message data cause])

let

(merr/let err [a 10
               b (inc a)
               c (inc b)]
  (if err
    (merr/message err)
    (str "c = " c)))
;; => "c = 12"
(merr/let err [a 10
               b (merr/error {:message "ERROR"})
               c (inc b)]
  (if err
    (merr/message err)
    (str "c = " c)))
;; => "ERROR"

→

(merr/-> 10 (+ 1) (- 1))
;; => 10
(merr/-> 10 ((fn [_] (merr/error))) (- 1))
;; => (merr/error)

→>

(merr/->> 10 (+ 1) (- 1))
;; => -10
(merr/->> 10 ((fn [_] (merr/error))) (- 1))
;; => (merr/error)

try

(merr/try (throw (ex-info "ERROR" {})))
;; => merr/error?

(require '[merr.helper :as merr.h])
;; => nil
(def custom-error (partial merr.h/typed-error ::custom-error-type))
;; => var?
(def custom-error? (partial merr.h/typed-error? ::custom-error-type))
;; => var?
(custom-error? (custom-error {:message "custom error"}))
;; => true

(derive ::sub-custom-error-type ::custom-error-type)
;; => nil
(custom-error? (merr/error {:type ::sub-custom-error-type}))
;; => true

clj-kondo --no-warnings --lint "$(clojure -Spath -Sdeps '{:deps {com.github.liquidz/merr {:mvn/version "LATEST"}}}')"