How to reproduce:
(t/cf (t/fn [m :- (t/HMap :optional {:a String} :complete? true)] (if-let [b (get m :a)] true)))
Observed result:
[[(t/HMap :optional {:a String} :complete? true) -> true :filters {:then tt, :else ff}] {:then tt, :else ff}]
Expected result (pseudeocode):
[(t/HMap :optional {:a String} :complete? true) -> (t/U nil true)]
This is what you get if you replace the if-let above with if.
Return type should be (t/Option true), as the if-let will result in a nil return if the :a key is not set on the map.
Details:
broz@macmicro:~$ grep try ~/.lein/profiles.clj
[lein-try "0.4.3"]
broz@macmicro:~$ lein try org.clojure/core.typed
nREPL server started on port 52406 on host 127.0.0.1 - nrepl://127.0.0.1:52406
REPL-y 0.3.5, nREPL 0.2.6
Clojure 1.6.0
Java HotSpot(TM) 64-Bit Server VM 1.8.0_40-b26
Docs: (doc function-name-here)
(find-doc "part-of-name-here")
Source: (source function-name-here)
Javadoc: (javadoc java-object-or-class-here)
Exit: Control+D or (exit) or (quit)
Results: Stored in vars *1, *2, *3, an exception in *e
user=> (require ['clojure.core.typed :as 't])
nil
user=> (t/cf (t/fn [m :- (t/HMap :optional {:a String} :complete? true)] (if-let [b (get m :a)] true)))
Initializing core.typed ...
Building core.typed base environments ...
Finished building base environments
"Elapsed time: 14055.732654 msecs"
core.typed initialized.
[[(t/HMap :optional {:a String} :complete? true) -> true :filters {:then tt, :else ff}] {:then tt, :else ff}]
