From 007b33f87d05722b65450128bb0ac9a78f4ecd1d Mon Sep 17 00:00:00 2001
From: Nikolaj Gade <nikolaj@ingemanngade.net>
Date: Thu, 26 Sep 2024 15:57:23 +0200
Subject: [PATCH] :jack_o_lantern: Function application

---
 a3/a3-handout/.gitignore              |  1 +
 a3/a3-handout/src/APL/Parser.hs       | 13 ++++++++++++-
 a3/a3-handout/src/APL/Parser_Tests.hs |  6 ++++++
 3 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 a3/a3-handout/.gitignore

diff --git a/a3/a3-handout/.gitignore b/a3/a3-handout/.gitignore
new file mode 100644
index 0000000..48a004c
--- /dev/null
+++ b/a3/a3-handout/.gitignore
@@ -0,0 +1 @@
+dist-newstyle
diff --git a/a3/a3-handout/src/APL/Parser.hs b/a3/a3-handout/src/APL/Parser.hs
index 7652024..cef0e31 100644
--- a/a3/a3-handout/src/APL/Parser.hs
+++ b/a3/a3-handout/src/APL/Parser.hs
@@ -75,6 +75,17 @@ pAtom =
       lString "(" *> pExp <* lString ")"
     ]
 
+pFExp :: Parser Exp
+pFExp = pAtom >>= chain
+  where
+    chain x =
+      choice
+        [ do
+            y <- pAtom
+            chain $ Apply x y,
+          pure x
+        ]
+
 pLExp :: Parser Exp
 pLExp =
   choice
@@ -82,7 +93,7 @@ pLExp =
         <$> (lKeyword "if" *> pExp)
         <*> (lKeyword "then" *> pExp)
         <*> (lKeyword "else" *> pExp),
-      pAtom
+      pFExp
     ]
 
 pExp1 :: Parser Exp
diff --git a/a3/a3-handout/src/APL/Parser_Tests.hs b/a3/a3-handout/src/APL/Parser_Tests.hs
index 618761a..1cc9ddd 100644
--- a/a3/a3-handout/src/APL/Parser_Tests.hs
+++ b/a3/a3-handout/src/APL/Parser_Tests.hs
@@ -64,5 +64,11 @@ tests =
         "Lexing edge cases"
         [ parserTest "2 " $ CstInt 2,
           parserTest " 2" $ CstInt 2
+        ],
+      testGroup
+        "FExp"
+        [ parserTest "x y" $ Apply (Var "x") (Var "y"),
+          parserTest "x y z" $ Apply (Apply (Var "x") (Var "y")) (Var "z"),
+          parserTest "x (y z)" $ Apply (Var "x") (Apply (Var "y") (Var "z"))
         ]
     ]