From 74b380efbcbdc1bb2558c2c5bced43fd36dff6fb Mon Sep 17 00:00:00 2001
From: Matthew Hall <hallmatthew314@gmail.com>
Date: Tue, 14 Feb 2023 17:05:01 +1300
Subject: Add lexing for negative integers

---
 DSL.hs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

(limited to 'DSL.hs')

diff --git a/DSL.hs b/DSL.hs
index 3244c7f..ea4c8c2 100644
--- a/DSL.hs
+++ b/DSL.hs
@@ -82,7 +82,12 @@ wsL :: DSLLexer
 wsL = buildDSLLexer (mult1 $ satisfy isSpace) (const T_WHITESPACE)
 
 intLiteralL :: DSLLexer
-intLiteralL = buildDSLLexer (mult1 $ satisfy isDigit) (T_INT_LITERAL . read)
+intLiteralL = buildDSLLexer go (T_INT_LITERAL . read)
+  where
+    go = do
+      sign   <- optional $ token '-'
+      digits <- mult1 $ satisfy isDigit
+      result $ maybe digits (:digits) sign
 
 mainLexer :: Parser Char [DSLToken]
 mainLexer = phrase $ mult1 $ firstOf subLexers
-- 
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