task.rb in dry-monads-1.0.0.beta2

- old
+ new

@@ -1,8 +1,10 @@
 require 'concurrent/promise'
 
+require 'dry/monads/unit'
 require 'dry/monads/curry'
+require 'dry/monads/conversion_stubs'
 
 module Dry
   module Monads
     # The Task monad represents an async computation. The implementation
     # is a rather thin wrapper of Concurrent::Promise from the concurrent-ruby.
@@ -66,10 +68,12 @@
           v = Undefined.default(value, block)
           new(Promise.fulfill(v))
         end
       end
 
+      include ConversionStubs[:to_maybe, :to_result]
+
       # @api private
       attr_reader :promise
       protected :promise
 
       # @api private
@@ -110,32 +114,10 @@
       def bind(&block)
         self.class.new(promise.flat_map { |value| block.(value).promise })
       end
       alias_method :then, :bind
 
-      # Converts to Result. Blocks the current thread if required.
-      #
-      # @return [Result]
-      def to_result
-        if promise.wait.fulfilled?
-          Result::Success.new(promise.value)
-        else
-          Result::Failure.new(promise.reason, RightBiased::Left.trace_caller)
-        end
-      end
-
-      # Converts to Maybe. Blocks the current thread if required.
-      #
-      # @return [Maybe]
-      def to_maybe
-        if promise.wait.fulfilled?
-          Maybe::Some.new(promise.value)
-        else
-          Maybe::None.new(RightBiased::Left.trace_caller)
-        end
-      end
-
       # @return [String]
       def to_s
         state = case promise.state
                 when :fulfilled
                   "value=#{ value!.inspect }"
@@ -242,10 +224,17 @@
       def apply(val = Undefined)
         arg = Undefined.default(val) { yield }
         bind { |f| arg.fmap { |v| curry(f).(v) } }
       end
 
+      # Maps a successful result to Unit, effectively discards it
+      #
+      # @return [Task]
+      def discard
+        fmap { Unit }
+      end
+
       private
 
       # @api private
       def curry(value)
         if defined?(@curried)
@@ -269,12 +258,16 @@
 
       # Task constructors.
       #
       # @api public
       module Mixin
-        Task = Task # @private
+        # @private
+        Task = Task
 
+        # @see Dry::Monads::Unit
+        Unit = Unit # @private
+
         # Created a mixin with the given executor injected.
         #
         # @param executor [Concurrent::AbstractExecutorService,Symbol]
         # @return [Module]
         def self.[](executor)
@@ -303,7 +296,9 @@
         end
 
         include Constructors
       end
     end
+
+    extend Task::Mixin::Constructors
   end
 end