Merge pull request #4211 from dearblue/proc-composition

Add proc composition feature (CRuby-2.6 compatible)

2 files changed, 21 insertions, 0 deletions

diff --git a/mrbgems/mruby-proc-ext/mrblib/proc.rb b/mrbgems/mruby-proc-ext/mrblib/proc.rb
index 789b7a3ac..abe9c7944 100644
--- a/mrbgems/mruby-proc-ext/mrblib/proc.rb
+++ b/mrbgems/mruby-proc-ext/mrblib/proc.rb
@@ -39,4 +39,12 @@ class Proc
     make_curry.call
   end
 
+  def <<(other)
+    ->(*args, &block) { call(other.call(*args, &block)) }
+  end
+
+  def >>(other)
+    ->(*args, &block) { other.call(call(*args, &block)) }
+  end
+
 end
diff --git a/mrbgems/mruby-proc-ext/test/proc.rb b/mrbgems/mruby-proc-ext/test/proc.rb
index 3e64bc103..1220841c8 100644
--- a/mrbgems/mruby-proc-ext/test/proc.rb
+++ b/mrbgems/mruby-proc-ext/test/proc.rb
@@ -77,6 +77,19 @@ assert('Kernel#proc') do
   end
 end
 
+assert "Proc#<< and Proc#>>" do
+  add3 = ->(n) { n + 3 }
+  mul2 = ->(n) { n * 2 }
+
+  f1 = mul2 << add3
+  assert_kind_of Proc, f1
+  assert_equal 16, f1.call(5)
+
+  f2 = mul2 >> add3
+  assert_kind_of Proc, f2
+  assert_equal 13, f2.call(5)
+end
+
 assert('mrb_proc_new_cfunc_with_env') do
   ProcExtTest.mrb_proc_new_cfunc_with_env(:test)
   ProcExtTest.mrb_proc_new_cfunc_with_env(:mruby)