[FLINK-1450] Add Fold operator to the Streaming api

• Type: New Feature
• Status: Resolved
• Priority: Minor
• Resolution: Implemented
• Affects Version/s: 0.9
• Fix Version/s: 0.9
• Component/s: API / DataStream
• Labels: starter
• Assignee: Akshay Dixit
• Reporter: Gyula Fora
• Created: 25/Jan/15 13:06
• Updated: 28/Feb/19 11:16
• Resolved: 15/Mar/15 10:06

Description

The streaming API currently doesn't support a fold operator.

This operator would work as the foldLeft method in Scala. This would allow effective implementations in a lot of cases where a the simple reduce is inappropriate due to different return types.