ekmett/semigroupoids — pull request #9 by S11001001 (2013-08-23 03:43:45+00:00)
Title: intercalate1 & intercalateMap1

```haskell
ghci> intercalate1 ", " $ "hello" :| ["how", "are", "you"]
"hello, how, are, you"
ghci> intercalate1 ", " $ "hello" :| []
"hello"
```