From 1aca426b414e38e909fb589fb5d801359f9434a6 Mon Sep 17 00:00:00 2001
From: rockofox <ofelix@pm.me>
Date: Sun, 15 Dec 2024 15:56:19 +0100
Subject: [PATCH] Thunk lambdas (fixes #18)

---
 lib/BytecodeCompiler.hs |  5 +++--
 lib/Parser.hs           | 10 +++++-----
 lib/Verifier.hs         |  2 +-
 share/std/test.in       |  2 +-
 4 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/lib/BytecodeCompiler.hs b/lib/BytecodeCompiler.hs
index 50738a9..164b363 100644
--- a/lib/BytecodeCompiler.hs
+++ b/lib/BytecodeCompiler.hs
@@ -634,9 +634,10 @@ compileExpr (Parser.Impl name for methods) expectedType = do
 compileExpr (Parser.Lambda args body) expectedType = do
     fId <- allocId
     curCon <- gets currentContext
+    let args' = if args == [Parser.Placeholder] then [] else args
     let name = "__lambda" ++ show fId
-    let def = Parser.FuncDef name args body
-    let dec = Parser.FuncDec name (replicate (length args + 1) expectedType) []
+    let def = Parser.FuncDef name args' body
+    let dec = Parser.FuncDec name (replicate (length args' + 1) Parser.Any) []
     let fun = Parser.Function [def] dec
     _ <- compileExpr fun expectedType
     lets' <- gets functions
diff --git a/lib/Parser.hs b/lib/Parser.hs
index df7a94b..4e7cf1c 100644
--- a/lib/Parser.hs
+++ b/lib/Parser.hs
@@ -85,13 +85,13 @@ binOpTable =
     , [binary "as" Cast]
     , [prefix "$" StrictEval]
     , [prefix "!" Not]
+    , [binary "++" ListAdd]
+    , [binary "**" Power, binary "*" Mul, binary "/" Div]
+    , [binary "+" Add, binary "-" Sub]
     , [binaryAny binaryFunctionCall]
     , -- , [prefix "-" UnaryMinus]
-      [binary "**" Power, binary "*" Mul, binary "/" Div]
-    , [binary "%" Modulo]
+      [binary "%" Modulo]
     , [binary ":" ListConcat]
-    , [binary "++" ListAdd]
-    , [binary "+" Add, binary "-" Sub]
     , --    , [binary ">>" Then]
       [binary "|>" Pipeline]
     , [binary ">>=" bindExpr]
@@ -488,7 +488,7 @@ listPattern = do
 lambda :: Parser Expr
 lambda = do
     symbol "\\"
-    args <- some (var <|> parens listPattern <|> array) <?> "lambda arguments"
+    args <- some (var <|> parens listPattern <|> array <|> placeholder) <?> "lambda arguments"
     symbol "->"
     Lambda args <$> expr <?> "lambda body"
 
diff --git a/lib/Verifier.hs b/lib/Verifier.hs
index b7c3114..a6e283e 100644
--- a/lib/Verifier.hs
+++ b/lib/Verifier.hs
@@ -377,7 +377,7 @@ verifyExpr (FuncCall name args (Position (start, _))) = do
     let eTypes = concatMap (\matchingBinding -> ([FancyError start (Set.singleton (ErrorFail ("Argument types do not match on " ++ name ++ ", expected: " ++ show matchingBinding.args ++ ", got: " ++ show argumentTypes))) | not fta])) matchingBindings
     return $ [FancyError start (Set.singleton (ErrorFail $ "Could not find relevant binding for " ++ name)) | null matchingBindings] ++ eArgs ++ eTypes ++ eNoMatchi
 verifyExpr (Lambda args body) = do
-    let argsAsBindings = map (\(Var name' _) -> VBinding{name = name', args = [], ttype = Any, generics = []}) args
+    let argsAsBindings = map (\case (Var name' _) -> VBinding{name = name', args = [], ttype = Any, generics = []}; Placeholder -> VBinding{name = "__placeholder", args = [], ttype = Any, generics = []}; _ -> error "Invalid lambda argument") args
     modify (\state -> state{frames = (VerifierFrame{bindings = Set.fromList argsAsBindings, ttypes = Map.empty, ftype = Any, fname = "__lambda"}) : frames state})
     bodyErrors <- verifyExpr body
     modify (\state -> state{frames = tail (frames state)})
diff --git a/share/std/test.in b/share/std/test.in
index c14a6ea..05b67a0 100644
--- a/share/std/test.in
+++ b/share/std/test.in
@@ -7,7 +7,7 @@ impl Monad for TestSuite = do
   sequence TestSuite{name: n, results: r} TestSuite{name: n2, results: r2} = TestSuite{name: n, results: r ++ r2}
 end
 
-let testCase (n: String f: (Any -> Bool)) : TestSuite = TestSuite{results: [TestResult{name: n, result: f 1}]}
+let testCase (n: String f: (Bool)) : TestSuite = TestSuite{results: [TestResult{name: n, result: f _}]}
 
 let evalTestSuite (suite: TestSuite) : IO = do
   let resultss = suite.results