core.typed not reporting type error in repl

Question

Here is a part of the example taken from core.typed github repo:

(ns typedclj.rps-async
  (:require [clojure.core.typed :as t]
            [clojure.core.async :as a]
            [clojure.core.typed.async :as ta]))

(t/defalias Move
  "A legal move in rock-paper-scissors"
  (t/U ':rock ':paper ':scissors))

(t/defalias PlayerName
  "A player's name in rock-paper-scissors"
  t/Str)

(t/defalias PlayerMove
  "A move in rock-paper-scissors. A Tuple of player name and move"
  '[PlayerName Move])

(t/defalias RPSResult
  "The result of a rock-paper-scissors match.
  A 3 place vector of the two player moves, and the winner"
  '[PlayerMove PlayerMove PlayerName])

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Implementation
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(t/ann MOVES (t/Vec Move))
(def MOVES [:rock :paper :scissors])

(t/ann BEATS (t/Map Move Move))
(def BEATS {:rock :scissors, :paper :rock, :scissors :paper})
(def BEATS {:a :b})

Note that in the last line I redefined BEATS to {:a :b}, which conflicts its type annotation, but when I eval this in the repl, no error is thrown. I was expecting an error because the latest version of core.typed is said to be able to report type errors at the runtime.

Here is the entire project.clj file:

            (defproject typedclj "0.1.0-SNAPSHOT"
                        :description "FIXME: write description"
                        :url "http://example.com/FIXME"
                        :license {:name "Eclipse Public License"
                                  :url  "http://www.eclipse.org/legal/epl-v10.html"}
                        :dependencies [[org.clojure/clojure "1.6.0"]
                                       [org.clojure/core.async "0.1.346.0-17112a-alpha" :exclusions [org.clojure/tools.analyzer.jvm]]
                                       [org.clojure/core.typed "0.2.92"]
                                       [clj-http "1.1.2"]
                                       [http-kit "2.1.18"]
                                       ]
                        :repl-options {:nrepl-middleware [clojure.core.typed.repl/wrap-clj-repl]}
                        :main ^:skip-aot typedclj.core
                        :target-path "target/%s"
                        :profiles {:uberjar {:aot :all}})

---

With core.typed 0.3.0-alpha2 this type error is nicely catched:

Type Error (/private/var/folders/5d/44ctbbln4dsflgzxph1dm8wr0000gn/T/form-init3488589171262628870.clj:36:12) Type mismatch:

Expected:   typedclj.rps-async/Move

Actual:     (t/Val :b)
in: :b


Type Error (/Users/kaiyin/personal_config_bin_files/workspace/typedclj/src/typedclj/rps_async.clj:36:12) Type mismatch:

Expected:   (t/Map typedclj.rps-async/Move typedclj.rps-async/Move)

Actual:     (t/HMap :mandatory {:a typedclj.rps-async/Move} :complete? true)
in: {:a :b}

Answer 1

You need to explicitly opt-in to implicit type checking. Change your ns form like so:

(ns ^:core.typed typedclj.rps-async
   ...)