From fd73ff713f4f90011b6f7337ae5a6115597f5a4d Mon Sep 17 00:00:00 2001
From: Mark Spanbroek <mark@spanbroek.net>
Date: Thu, 15 Apr 2021 09:41:32 +0200
Subject: [PATCH] Adds `failure` overload that uses `result` to determine type

---
 Readme.md                   |  8 ++++----
 questionable/results.nim    |  6 ++++++
 testmodules/result/test.nim | 11 +++++++++--
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/Readme.md b/Readme.md
index f67bed2..adc5580 100644
--- a/Readme.md
+++ b/Readme.md
@@ -146,16 +146,16 @@ proc example: ?!int =
   # either return an integer or an error
 ```
 
-Assigning values is done using the `success` and `failure` procs:
+Results can be made using the `success` and `failure` procs:
 
 ```nim
 proc works: ?!seq[int] =
   # always returns a Result holding a sequence
-  @[1, 1, 2, 2, 2].success
+  success @[1, 1, 2, 2, 2]
 
 proc fails: ?!seq[int] =
-  # always returns a Result holding a ValueError
-  seq[int].failure newException(ValueError, "something went wrong")
+  # always returns a Result holding an error
+  failure "something went wrong"
 ```
 
 ### Binding, chaining, fallbacks and operators
diff --git a/questionable/results.nim b/questionable/results.nim
index 3ad1655..fc7dfa0 100644
--- a/questionable/results.nim
+++ b/questionable/results.nim
@@ -21,6 +21,12 @@ proc failure*(T: type, error: ref CatchableError): ?!T =
 proc failure*(T: type, message: string): ?!T =
   T.failure newException(ResultFailure, message)
 
+template failure*(error: ref CatchableError): auto =
+  err error
+
+template failure*(message: string): auto =
+  failure newException(ResultFailure, message)
+
 proc isSuccess*[T](value: ?!T): bool =
   value.isOk
 
diff --git a/testmodules/result/test.nim b/testmodules/result/test.nim
index 7f4b84c..5fdf56a 100644
--- a/testmodules/result/test.nim
+++ b/testmodules/result/test.nim
@@ -150,13 +150,20 @@ suite "result":
     check 42.success.option == 42.some
     check int.failure(error).option == int.none
 
+  test "failure can be used without type parameter in procs":
+    proc fails: ?!int =
+      failure "some error"
+
+    check fails().isFailure
+    check fails().error.msg == "some error"
+
   test "examples from readme work":
 
     proc works: ?!seq[int] =
-      @[1, 1, 2, 2, 2].success
+      success @[1, 1, 2, 2, 2]
 
     proc fails: ?!seq[int] =
-      seq[int].failure newException(ValueError, "something went wrong")
+      failure "something went wrong"
 
     # binding:
     if x =? works():