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I'm passing around a partially applied function. The full signature is: import Data.Map as Map -- Update the correct bin of the histogram based on the min value, bin width, -- the histogram stored as a map, and the actual value we are interested in. updateHist :: Double -> Double -> Map.Map Bin Double -> Double -> Map.Map Bin Double The function updates a Map which stores data for a histogram. The first two parameters give the bottom bounds of data we are interested, the next is the bin width for the histogram. I fill these values in when the program starts up and pass the partially applied function all over the module. This means I have a ton of functions with a signature like: -- Extra the data out of the string and update the histogram (in the Map) with it. doSomething :: String -> (Map.Map Bin Double -> Double -> Map.Map Bin Double) -> Map.Map Bin Double This is all fine and dandy, but writing "(Map.Map Bin Double -> Double -> Map.Map Bin Double)" is rather verbose. I'd like to replace them all with "UpdateHistFunc" as a type but for some reason I keep failing. I tried: newtype UpdateHistFunc = Map.Map Bin Double -> Double -> Map.Map Bin Double This failed with the error: HistogramForColumn.hs:84:44: parse error on input `->' What am I doing wrong?

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