Haskell accessing type-classes parameters problem

Question

This is prob an easy question but I just could not find the answer for this:

How can I access the parameters of a custom type?

Lets say my code is like this: (anotherFunc is only there to help me access the parameter)

data Shape = (Shape Color [Dimension])

func :: [Shape] -> [Shape]
func (x:xs) = anotherFunc x : func xs

anotherFunc :: [Shape] -> [Shape]
anotherFunc (Shape Color (x:xs)) = <some simple operations>

is there something similar to this??

func ( (Shape Color (x:xs)):shapes )

many thx!!

Maybe this helps you.

freestyle
– freestyle

2020-02-05 15:47:52 +00:00
Commented Feb 5, 2020 at 15:47 — freestyle
– freestyle, Commented Feb 5, 2020 at 15:47

chepner · Accepted Answer · 2020-02-05 20:39:12Z

1

There is something very similar to that.

func ((Shape _ (x:xs)):shapes) = ...

However, your func just reimplements map, so you can use that and continue to use anotherFunc (which can be defined locally if you'd prefer):

func = map anotherFunc
  where anotherFunc (Shape c ds) = ...

answered Feb 5, 2020 at 20:39

chepner

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