utprimum at gmail.com
Wed Apr 22 18:20:57 UTC 2020
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
Il giorno mer 22 apr 2020 alle ore 20:11 Alexander Chen <
alexander at chenjia.nl> ha scritto:
> *data TisanInteger = Tisan Integer*
> *instance Eq (Tisan Integer) where (Tisan v) == (Tisan v') = v == v'*
> *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?
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