Add Try.astuple

Author: tkf

docs/src/index.md

@@ -16,6 +16,7 @@ Try.unwrap_err
 Try.oktype
 Try.errtype
 Try.map
+Try.astuple
 ```
 
 ## Short-circuit evaluation

src/Try.jl

@@ -35,6 +35,7 @@ struct IsOkError <: InternalPrelude.Exception
 end
 
 function map end
+function astuple end
 
 macro and_return end
 function var"@?" end

src/branch.jl

@@ -161,6 +161,15 @@ macro or(ex, rest...)
     end
 end
 
+function Try.astuple(result)
+    br = branch(result)
+    if br isa Break
+        ()
+    else
+        (valueof(br),)
+    end
+end
+
 ###
 ### Currying
 ###

src/docs/astuple.md

@@ -0,0 +1,25 @@
+    Try.astuple(result) -> (value,) or ()
+    Try.astuple(Ok(value)) -> (value,)
+    Try.astuple(::Err) -> ()
+    Try.astuple(Some(value)) -> (value,)
+    Try.astuple(nothing) -> ()
+
+Return a singleton tuple with the value if the result is "successful"; return an empty tuple
+otherwise.
+
+# Examples
+```julia
+julia> using Try
+
+julia> Try.astuple(Ok(1))
+(1,)
+
+julia> Try.astuple(Err(1))
+()
+
+julia> Try.astuple(Some(1))
+(1,)
+
+julia> Try.astuple(nothing)
+()
+```