I see the <$> notation often in the Plutus/Haskell code but have no idea what it means. I understand that $ alone is a parenthesis replacement. Is <$> similar? Does it suggest enclosing parenthesis?

Example from the deploy.hs script in week 3.

dataToScriptData :: Data -> ScriptData
dataToScriptData (Constr n xs) = ScriptDataConstructor n $ dataToScriptData  xs
dataToScriptData (Map xs)      = ScriptDataMap [(dataToScriptData x, dataToScriptData y) | (x, y)  xs
dataToScriptData (I n)         = ScriptDataNumber n
dataToScriptData (B bs)        = ScriptDataBytes bs

So hard to do a Google search on Haskell's cryptic syntax!

2 Answers 2


It's a functor map which is essentially an fmap function for the functor class. This might be of some use: https://www.fpcomplete.com/haskell/tutorial/operators/


For Haskell questions of this sort Hoogle is the ultimate resource.

For operators like <$> you need to enclose them in parenthesis eg (<$>).

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