How to make damlc ide parse {-# LANGUAGE -#}?

When I run daml damlc ide to use the LSP server with vim, I need to pass it explicit arguments --ghc-option -X_____ to enable a language feature.

Is there a way to automate this, so that the LSP server infers these from the {-# LANGAUGE _____ #-} pragma in my source code, rather than having to pass them in explicitly?

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damlc should always parse that pragma both in the IDE mode as well as in daml build. Do you have a concrete example where this doesn’t work?

It happens every time I start the IDE from vim. It executes daml damlc ide indirectly, as far as I know.

Can you reproduce it in VSCode? All the logic for this should be in damlc not in the editor-specific side so it shouldn’t be specific to vim.

Looks like I can reproduce it:


Just ran daml init and then created daml/Main.daml like above. The error says

/home/luciano/src/testextensions/daml/Main.daml:5:6: error:
Illegal declaration of a type or class operator ‘:+:’
Use TypeOperators to declare operators in type and declarations

The lanugage pragma needs to be above the module header not below. So try the following:

{-# LANGUAGE TypeOperators #-}
module Main where


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