ported over jruby's fix for Proc#curry, this closes #2951

tak1n · tak1n · commit e5def49e2a69 · 2015-05-23T22:33:04.000+02:00
diff --git a/kernel/common/proc.rb b/kernel/common/proc.rb
@@ -14,6 +14,23 @@ def self.__from_block__(env)
     end
   end
 
+  def self.__make_curry_proc__(proc, passed, arity)
+    is_lambda = proc.lambda?
+    passed.freeze
+
+    __send__((is_lambda ? :lambda : :proc)) do |*argv, &passed_proc|
+      my_passed = passed + argv
+      if my_passed.length < arity
+        if !passed_proc.nil?
+          warn "#{caller[0]}: given block not used"
+        end
+        __make_curry_proc__(proc, my_passed, arity)
+      else
+        proc.call(*my_passed)
+      end
+    end
+  end
+
   def self.new(*args)
     env = nil
 
@@ -94,17 +111,7 @@ def curry(curried_arity = nil)
 
     args = []
 
-    my_self = self
-    m = lambda? ? :lambda : :proc
-    f = __send__(m) {|*x|
-      call_args = args + x
-      if call_args.length >= my_self.arity
-        my_self[*call_args]
-      else
-        args = call_args
-        f
-      end
-    }
+    f = Proc.__make_curry_proc__(self, [], arity)
 
     f.singleton_class.send(:define_method, :binding) {
       raise ArgumentError, "cannot create binding from f proc"
diff --git a/spec/ruby/core/proc/curry_spec.rb b/spec/ruby/core/proc/curry_spec.rb
@@ -59,17 +59,17 @@
     l = lambda { |*a| }
     l.curry.arity.should == -1
   end
-  
+
   it "produces Procs that raise ArgumentError for #binding" do
     lambda do
       @proc_add.curry.binding
     end.should raise_error(ArgumentError)
   end
-  
+
   it "produces Procs that return [[:rest]] for #parameters" do
     @proc_add.curry.parameters.should == [[:rest]]
   end
-  
+
   it "produces Procs that return nil for #source_location" do
     @proc_add.curry.source_location.should == nil
   end
@@ -79,6 +79,16 @@
 
     instance_exec(3, &curried).should == 6
   end
+
+  it "combines arguments and calculates incoming arity accurately for successively currying" do
+    l = lambda{|a,b,c| a+b+c }
+    l1 = l.curry.call(1)
+    # the l1 currying seems unnecessary, but it triggered the original issue
+    l2 = l1.curry.call(2)
+
+    l2.curry.call(3).should == 6
+    l1.curry.call(2,3).should == 6
+  end
 end
 
 describe "Proc#curry with arity argument" do
