From 88481dd285ccbc7324b390dde9d6c55da1c9a212 Mon Sep 17 00:00:00 2001
From: Zoe Roux <zoe.roux@sdg.moe>
Date: Wed, 3 Nov 2021 10:24:39 +0100
Subject: [PATCH] Creating a lisp parser

---
 src/BasicParser.hs | 13 +++++++------
 src/LispParser.hs  | 15 ++++++++++-----
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/src/BasicParser.hs b/src/BasicParser.hs
index b1bcfd7..a2dfb24 100644
--- a/src/BasicParser.hs
+++ b/src/BasicParser.hs
@@ -54,14 +54,17 @@ pCharIf predicate = Parser subParse
             | otherwise = (Nothing, c:cs)
 
 pUntil :: (Char -> Bool) -> Parser String
-pUntil predicate = many $ pCharIf (not . predicate)
+pUntil predicate = some $ pCharIf (not . predicate)
+
+pToken :: Parser String
+pToken = pUntil $ \x -> isSpace x || x == ')' || x == '('
 
 pDigit :: Parser Char
 pDigit = pCharIf isDigit
 
 pInt :: Parser Int
-pInt = (pCharIf (== '-') >> (negate . read <$> some pDigit))
-    <|> read <$> some pDigit
+pInt =  (pCharIf (== '-') >> negate <$> unMaybe (readMaybe <$> pToken))
+    <|> unMaybe (readMaybe <$> pToken)
 
 unMaybe :: Parser (Maybe a) -> Parser a
 unMaybe p = Parser $ \x -> case parse p x of
@@ -76,9 +79,7 @@ pFloat =
     <|> unMaybe floating
     where
         floating :: Parser (Maybe Float)
-        floating = do
-            value <- many $ pCharIf (\x -> isNumber x || x == '.')
-            return $ readMaybe value
+        floating = readMaybe <$> pToken
 
 tokenify :: Parser a -> Parser a
 tokenify input =
diff --git a/src/LispParser.hs b/src/LispParser.hs
index 1f64f10..8581eaa 100644
--- a/src/LispParser.hs
+++ b/src/LispParser.hs
@@ -1,14 +1,19 @@
+module LispParser where
+
 import BasicParser
-import Expressions
-import Control.Applicative
-import Data.Char
+    ( Parser, pCharIf, pUntil, pInt, pFloat, tokenify, pToken )
+import Expressions ( SExpr(..), Atom(..) )
+import Control.Applicative ( Alternative(some, (<|>)) )
 
 pAtom :: Parser Atom
 pAtom =
     AInt <$> pInt <|>
     AFloat <$> pFloat <|>
     pCharIf (== '"') *> (AString <$> pUntil (== '"')) <* pCharIf (== '"') <|>
-    ASymbol <$> pUntil isSpace
+    ASymbol <$> pToken
 
 pSExpr :: Parser SExpr
-pSExpr = pCharIf (== '(') *> (SExpr <$> some (tokenify pAtom)) <* pCharIf (== ')')
\ No newline at end of file
+pSExpr = pCharIf (== '(') *> (SExpr <$> some (tokenify pAtom)) <* pCharIf (== ')')
+
+pLisp :: Parser [SExpr]
+pLisp = some $ tokenify pSExpr
\ No newline at end of file