I do not understand why the DuplicateRecordFields language pragma is causing a compile time error in a template haskell splice.
Example:
-- TypeModule.hs
{-# LANGUAGE DuplicateRecordFields #-}
module TypeModule where
data A = A {foo :: Int} deriving Show
-- ThModule.hs
{-# LANGUAGE TemplateHaskell #-}
module ThModule where
import Language.Haskell.TH
import Language.Haskell.TH.Syntax
import TypeModule
mkLambda :: Q [Dec]
mkLambda = [d| func :: A -> Int; func = foo |]
-- Lib.hs
module Lib where
import TypeModule
import ThModule
$mkLambda
{-
Illegal variable name: ‘$sel:foo:A’
When splicing a TH declaration: func_0 = (TypeModule.$sel:foo:A)
|
8 | $mkLambda
| ^^^^^^^^
-}
When I remove the DuplicateRecordFields pragma, the compile time error goes away.
I am using the DuplicateRecordFields pragma because I am parsing a number of different JSON objects which are responses from a REST API, and many of these JSON objects contain fields with identical names.
Right now I am looking for a way that does not use DuplicateRecordFields, but at the least I would like to understand what in particular is causing the compiler trouble.
