Remove Ambiguous Error

Questions
1

Hi,

I have a daml file that use both TextMap and Map.
When using insert, I get an error that says insert can be in TextMap or in Map and that it can’t decide even though the type is Map Party MyData

Any idea?

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2

You can either be explicit by using qualified imports

import DA.TextMap as TM
import DA.Next.Map as M

and then use M.insert.

Or you hide the function from one of the imports:

import DA.TextMap hiding (insert, empty)
import DA.Next.Map

and then just use insert and empty as usual.

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3

Or – third option – make one a qualified import:

import DA.TextMap qualified as TM
import DA.Next.Map

Now insert refers to DA.Next.Map.insert, and to use the TextMap version you have to use TM.insert.

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4

Bit of a syntax quirk we inherited from Haskell, but worth pointing out the tradeoffs of each form.

import Lib

will import each symbol s in Lib as s, as if they had been defined in the current module.

import qualified Lib

will import each symbol s in Lib as Lib.s.

import qualified Lib as L

will import each symbol s in Lib as L.s

import Lib as L

will import each symbol s in Lib as both L.s and s. I personally recommend never using this one.

Finally, for each form, you can limit the set of imported symbols by either whitelisting:

import Lib (f, g)

or blacklisting:

import Lib hiding (f, g)

For your case, I would recommend importing both modules qualified. But then again, I’m a bit biased, as I tend to always import all my modules qualified.

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