Hi,

data TisanInteger = Tisan Integer

instance Eq (Tisan Integer) where (Tisan v) == (Tisan v') = v == v'

I think the part in red is the error: you should write TisanInteger instead (with no space between Tisan and Integer):

This is because there you should put the name of the data, not its definition.

Best,

Il giorno mer 22 apr 2020 alle ore 20:11 Alexander Chen <alexander@chenjia.nl> ha scritto:

Hi,

data TisanInteger = Tisan Integer

instance Eq (Tisan Integer) where (Tisan v) == (Tisan v') = v == v'

prelude>
Instance_testen.hs:7:14: error:
Not in scope: type constructor or class ‘Tisan’
A data constructor of that name is in scope; did you mean DataKinds?
|
7 | instance Eq (Tisan Integer) where (Tisan v) == (Tisan v') = v == v' | ^^^^^
[1 of 1] Compiling Main ( Instance_testen.hs, interpreted )
Failed, no modules loaded.

what am i doing wrong?

best,

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