From aeabc955c8b107e5467cb6b384b40320fb453176 Mon Sep 17 00:00:00 2001
From: Inari Listenmaa <inari.listenmaa@gmail.com>
Date: Fri, 31 Jul 2020 15:05:46 +0200
Subject: [PATCH] Remove characters that aren't allowed in Haskell data types.

GF allows more characters in its types, as long as they are inside
single quotes. E.g. 'VP/Object' is a valid name for a GF category,
but not for a Haskell data type.
---
 src/compiler/GF/Compile/PGFtoHaskell.hs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/compiler/GF/Compile/PGFtoHaskell.hs b/src/compiler/GF/Compile/PGFtoHaskell.hs
index e1fbc49aa..41f928d31 100644
--- a/src/compiler/GF/Compile/PGFtoHaskell.hs
+++ b/src/compiler/GF/Compile/PGFtoHaskell.hs
@@ -40,8 +40,10 @@ grammar2haskell opts name gr = foldr (++++) [] $
           gadt = haskellOption opts HaskellGADT
           dataExt = haskellOption opts HaskellData
           lexical cat = haskellOption opts HaskellLexical && isLexicalCat opts cat
-          gId | haskellOption opts HaskellNoPrefix = id
-              | otherwise = ("G"++)
+          gId | haskellOption opts HaskellNoPrefix = rmForbiddenChars
+              | otherwise = ("G"++) . rmForbiddenChars
+          -- GF grammars allow weird identifier names inside '', e.g. 'VP/Object'
+          rmForbiddenChars = filter (`notElem` "'!#$%&*+./<=>?@\\^|-~")
           pragmas | gadt = ["{-# OPTIONS_GHC -fglasgow-exts #-}","{-# LANGUAGE GADTs #-}"]
                   | dataExt = ["{-# LANGUAGE DeriveDataTypeable #-}"]
                   | otherwise = []