convert (limited) letrec

golden/factorial/exec

@@ -0,0 +1,2 @@
+ret > ExitSuccess
+out > 720

golden/factorial/source.scm

@@ -0,0 +1,5 @@
+(letrec ((fac (λ (n)
+                (if (zero? n)
+                    1
+                    (* n (fac (- n 1)))))))
+  (fac 6))

src/Gyehoek/CPS/Convert.hs

@@ -14,6 +14,10 @@ import Control.Monad.Cont qualified as Cont
 import Control.Lens
 import qualified Data.List.NonEmpty as NE
 import qualified Gyehoek.Sexp
+import Data.String.Interpolate (i)
+import Data.Functor (unzip)
+import Data.List (List)
+import Prelude hiding (unzip)
 
 
 -- 뻘짓이어라
@@ -45,11 +49,10 @@ convert (Scm.ExpPrim p) k =
 
 convert (Scm.ExpLambda xs e) k = do
   f <- gensym' "λ-body"
-  ktail <- gensym' "λ-tail"
+  lam <- convertLambda xs e
-  m <- convert e $ \e' -> pure $ ExpContinue ktail [e']
   ke <- k $ ValVar f
   pure [cps|
-    (letrec ((#{f} (λ (##{xs} #{ktail}) #{m})))
+    (letrec ((#{f} #{lam}))
       #{ke})
   |]
 
@@ -80,7 +83,24 @@ convert (Scm.ExpLet bs e) k =
         (continue #{kbody} ##{rhss'}))
     |]
 
-convert _ k = _
+convert (Scm.ExpLetRec bs m) k = do
+  let bs' = bs & each . _2 %~ (^?! #ExpLambda)
+  let conv = traverseOf _2 (uncurry $ convertLambda @es)
+  bs'' <- traverse conv bs'
+  m' <- convert m k
+  pure [cps|
+    (letrec #{bs''} #{m'})
+  |]
+
+-- convert e k = error [i|unimplemented expr: #{e}|]
+
+convertLambda
+  :: GenSym :> es
+  => List Name -> Scm.Exp -> Eff es Lambda
+convertLambda bs m = do
+  ktail <- gensym' "lambda-tail"
+  m' <- convert m $ pure . ExpContinue ktail . (:[])
+  pure [cps|(λ (##{bs} #{ktail}) #{m'})|]
 
 convertProgram :: forall es. (GenSym :> es) => Scm.Program -> Eff es Program
 convertProgram p =

test/Gyehoek/Test/Golden.hs

@@ -25,6 +25,7 @@ brokenWasmTests =
   , "fn-of-fn"
   , "let-fn"
   , "apply2"
+  , "factorial"
   ]
 
 brokenStackifyTests :: List String