{"action":"opened","issue":{"url":"https://api.github.com/repos/neo4j/neo4j/issues/8204","repository_url":"https://api.github.com/repos/neo4j/neo4j","labels_url":"https://api.github.com/repos/neo4j/neo4j/issues/8204/labels{/name}","comments_url":"https://api.github.com/repos/neo4j/neo4j/issues/8204/comments","events_url":"https://api.github.com/repos/neo4j/neo4j/issues/8204/events","html_url":"https://github.com/neo4j/neo4j/issues/8204","id":183840900,"number":8204,"title":" Surprising Type Error when accessing a nested list and then concatenating it to another list","user":{"login":"jacknoble","id":1051472,"avatar_url":"https://avatars.githubusercontent.com/u/1051472?v=3","gravatar_id":"","url":"https://api.github.com/users/jacknoble","html_url":"https://github.com/jacknoble","followers_url":"https://api.github.com/users/jacknoble/followers","following_url":"https://api.github.com/users/jacknoble/following{/other_user}","gists_url":"https://api.github.com/users/jacknoble/gists{/gist_id}","starred_url":"https://api.github.com/users/jacknoble/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jacknoble/subscriptions","organizations_url":"https://api.github.com/users/jacknoble/orgs","repos_url":"https://api.github.com/users/jacknoble/repos","events_url":"https://api.github.com/users/jacknoble/events{/privacy}","received_events_url":"https://api.github.com/users/jacknoble/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":0,"created_at":"2016-10-19T01:03:24Z","updated_at":"2016-10-19T01:03:24Z","closed_at":null,"body":"Hi! I found this behavior strange enough that it should probably be considered a bug. \r\n\r\nIn Cypher lists can be concatenated\r\n```return [] + [1]``` => ```[1]```\r\nand the head of a list can be accessed by the `head` function\r\n```return head([[], 1])``` => ```[]```\r\n\r\nAnd naturally one expects to be able to compose these expressions. But that's a type error.\r\n```return head([[],1]) + [1]``` => ```Type mismatch: expected Collection<Any> but was Collection<Integer>```\r\n\r\nI would expect this expression to return ```[1]```. Cypher users probably shouldn't ever see errors related to typed collections right?\r\n\r\n(Discovered using Neo4j 3.0.4, that's probably sufficient for reproducing)"}}
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