How to chain `<-`?

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1

Hello,

I have this piece of code:

  trgls     <- trianglesIO
  triangles <- newIORef trgls

How can I get triangles from trianglesIO in one line?

2

I’ve found: triangles <- trianglesIO >>= newIORef.

3

You can also use the flipped version to keep the information flow direction right to left:

  triangles <- newIORef =<< trianglesIO

The .. <- .. is built in syntax while >>= and =<< are normal operators which could have be defined by users. User defined operators will always be more flexible than built in syntax.

4

Alternatively, use more exact names:

  initial <- initTriangles
  current <- newIORef initial