Allow optional binding to vars

questionable/options.nim

@@ -1,4 +1,5 @@
 import std/options
+import std/macros
 import ./chaining
 import ./operators
 
@@ -26,6 +27,14 @@ template `=?`*[T](name: untyped{nkIdent}, option: ?T): bool =
   template name: T {.used.} = option.unsafeGet()
   option.isSome
 
+macro `=?`*[T](variable: untyped{nkVarTy}, option: ?T): bool =
+  let name = variable[0]
+  quote do:
+    var `name` : typeof(`option`.unsafeGet())
+    if `option`.isSome:
+      `name` = `option`.unsafeGet()
+    `option`.isSome
+
 template `|?`*[T](option: ?T, fallback: T): T =
   if option.isSome:
     option.unsafeGet()

questionable/results.nim

@@ -1,3 +1,4 @@
+import std/macros
 import ./resultsbase
 import ./options
 import ./operators
@@ -41,6 +42,14 @@ template `=?`*[T](name: untyped{nkIdent}, value: ?!T): bool =
   template name: T {.used.} = value.unsafeGet()
   value.isOk
 
+macro `=?`*[T](variable: untyped{nkVarTy}, option: ?!T): bool =
+  let name = variable[0]
+  quote do:
+    var `name` : typeof(`option`.unsafeGet())
+    if `option`.isOk:
+      `name` = `option`.unsafeGet()
+    `option`.isOk
+
 proc option*[T,E](value: Result[T,E]): ?T =
   if value.isOk:
     value.unsafeGet.some

testmodules/options/test.nim

@@ -74,6 +74,19 @@ suite "optionals":
     if a =? a:
       check a == 42
 
+  test "=? works with var":
+    if var a =? 1.some and var b =? 2.some:
+      check a == 1
+      inc a
+      check a == b
+      inc b
+      check b == 3
+    else:
+      fail
+
+    if var a =? int.none:
+      fail
+
   test "unary operator `-` works for options":
     check -(-42.some) == 42.some
     check -(int.none) == int.none

testmodules/result/test.nim

@@ -78,6 +78,19 @@ suite "result":
     if a =? a:
       check a == 42
 
+  test "=? works with var":
+    if var a =? 1.success and var b =? 2.success:
+      check a == 1
+      inc a
+      check a == b
+      inc b
+      check b == 3
+    else:
+      fail
+
+    if var a =? int.failure(error):
+      fail
+
   test "catch can be used to convert exceptions to results":
     check parseInt("42").catch == 42.success
     check parseInt("foo").catch.error of ValueError