return, pushcall
build / build (push) Failing after 1m26s

This commit is contained in:
2026-08-29 07:25:06 -06:00
parent 5ccb3f3e1a
commit 7085ef0685
6 changed files with 307 additions and 245 deletions
-88
View File
@@ -1,88 +0,0 @@
* example
#+begin_src scheme
(letrec ((fac (λ (n)
(if (zero? n)
1
(* n (fac (- n 1)))))))
(fac 3))
#+end_src
#+begin_src scheme
(λ (ktail0)
(letrec ((fac
(λ (n ktail1)
(zero?
n
(κ (x0)
(if x0
(continue ktail1 1)
(- n 1
(κ (x1)
(fac x1
(κ (x2)
(* n x2 ktail1)))))))))))
(fac 3)))
#+end_src
#+begin_example
n ktail1
| |
| | x0
| | |
| | ^
| |
| | x1
| | |
| | ^
| |
| | x2
| | |
^ ^ ^
#+end_example
#+begin_src scheme
(define $fac-c0
(pop! %x0 0) ; [ x0 $fac-c0 n $fac ktail1 ]
(if %x0 ; [ $fac-c0 n $fac ktail1 ]
;; every variable but `ktail1' is dead so we pop them all.
;; this probably means that `if' should take two continuations
;; rather than two blocks.
(then (pop! %_) ; [ $fac-c0 n $fac ktail1 ]
(pop! %_) ; [ n $fac ktail1 ]
(pop! %_) ; [ $fac ktail1 ]
(push! 1) ; [ ktail1 ]
(return 1)) ; [ 1 ktail1 ]
(else (load! %n 1) ; [ $fac-c0 n $fac ktail1 ]
(prim %x1 (- %n 1)) ; [ $fac-c0 n $fac ktail1 ]
(push! $fac-c1) ; [ $fac-c0 n $fac ktail1 ]
(push! $fac) ; [ $fac-c1 $fac-c0 n $fac ktail1 ]
(push! %x1) ; [ $fac $fac-c1 $fac-c0 n $fac ktail1 ]
(call 1) ; [ x1 $fac $fac-c1 $fac-c0 n $fac ktail1 ]
)))
(define $fac-c1
(pop! %x2) ; [ x2 $fac-c1 $fac-c0 n $fac ktail1 ]
(load! %n 3) ; [ $fac-c1 $fac-c0 n $fac ktail1 ]
(prim %x3 (* %n %x2))
(push! %x3) ; [ $fac-c1 $fac-c0 n $fac ktail1 ]
(return 1) ; [ x3 $fac-c1 $fac-c0 n $fac ktail1 ]
)
(define $fac
(load! %ktail1 2) ; [ n $fac ktail1 ]
(load! %n 0) ; [ n $fac ktail1 ]
(push! $fac-c0) ; [ n $fac ktail1 ]
(push! $zero?) ; [ $fac-c0 n $fac ktail1 ]
(push! %n) ; [ $zero? $fac-c0 n $fac ktail1 ]
(call 1) ; [ n $zero? $fac-c0 n $fac ktail1 ]
)
(define $start
(push! $fac) ; [ $start ktail0 ]
(push! 3) ; [ $fac $start ktail0 ]
(tail-call 1) ; [ 3 $fac $start ktail0 ]
;; ↑ `tail-call' knows how to dispose of the caller's stack frame.
)
#+end_src
+75 -43
View File
@@ -7,62 +7,94 @@ this worked quite well until it became time to implement ~call/cc~.
we are considering making the following alterations to the VM:
- explicitly segment the stack into frames.
- passing procedures and return addresses on the stack.
- new instructions:
+ ~(tail-call /n/)~
+ ~(call /n/)~
+ ~(load /r/ /n/)~
+ ~(return /n/)~
* scratchpad
** Scheme source
#+begin_src scheme
(* 2 (call/cc
(λ (cc)
(begin (cc 6)
3))))
(letrec ((fac (λ (n)
(if (zero? n)
1
(* n (fac (- n 1)))))))
(fac 3))
#+end_src
** CPS
#+begin_src scheme
(λ (ktail0)
(letrec ((with-cc
(λ (cc ktail1)
(letrec ((k0 (κ (_)
(continue ktail1 3))))
(cc 6 k0)))))
(prim (call/cc with-cc)
(κ (x1)
(prim (* 2 x1)
(κ (x2) (continue ktail0 x2)))))))
(λ (ktail0)
(letrec ((fac
(λ (n ktail1)
(zero?
n
(κ (x0)
(if x0
(continue ktail1 1)
(- n 1
(κ (x1)
(fac x1
(κ (x2)
(* n x2 ktail1)))))))))))
(fac 3)))
#+end_src
** stack VM
#+begin_example
n ktail1
| |
| | x0
| | |
| | ^
| |
| | x1
| | |
| | ^
| |
| | x2
| | |
^ ^ ^
#+end_example
#+begin_src scheme
;; (call n) expects `n' values on the stack as arguments. then the
;; procedure is expected at index `n', and the return continuation
;; should be at `n+1'.
(define $fac-c0
(pop! %x0 0) ; [ x0 $fac-c0 n $fac ktail1 ]
(if %x0 ; [ $fac-c0 n $fac ktail1 ]
;; every variable but `ktail1' is dead so we pop them all.
;; this probably means that `if' should take two continuations
;; rather than two blocks.
(then (push! 1) ; [ $fac-c0 n $fac ktail1 ]
(return 1)) ; [ 1 $fac-c0 n $fac ktail1 ]
(else (load %n 1) ; [ $fac-c0 n $fac ktail1 ]
(prim %x1 (- %n 1)) ; [ $fac-c0 n $fac ktail1 ]
(push! $fac-c1) ; [ $fac-c0 n $fac ktail1 ]
(push! $fac) ; [ $fac-c1 $fac-c0 n $fac ktail1 ]
(push! %x1) ; [ $fac $fac-c1 $fac-c0 n $fac ktail1 ]
(call 1) ; [ x1 $fac $fac-c1 $fac-c0 n $fac ktail1 ]
)))
(define $k0
(pop! %_) ; [ _ ret ]
(push! 3) ; [ ret ]
(tail-call 1) ; [ 3 ret ]
)
(define $fac-c1
(pop! %x2) ; [ x2 $fac-c1 $fac-c0 n $fac ktail1 ]
(load %n 3) ; [ $fac-c1 $fac-c0 n $fac ktail1 ]
(prim %x3 (* %n %x2))
(push! %x3) ; [ $fac-c1 $fac-c0 n $fac ktail1 ]
(return 1) ; [ x3 $fac-c1 $fac-c0 n $fac ktail1 ]
)
(define $with-cc
(pop! %cc) ; [ cc ret ]
(push! $k0) ; [ ret ]
(push! %cc) ; [ $k0 ret ]
(push! 6) ; [ cc $k0 ret ]
;; call a procedure with one argument.
(call 1) ; [ 6 cc $k0 ret ]
)
(define $fac
(load %ktail1 2) ; [ n $fac ktail1 ]
(load %n 0) ; [ n $fac ktail1 ]
(push! $fac-c0) ; [ n $fac ktail1 ]
(push! $zero?) ; [ $fac-c0 n $fac ktail1 ]
(push! %n) ; [ $zero? $fac-c0 n $fac ktail1 ]
(call 1) ; [ n $zero? $fac-c0 n $fac ktail1 ]
)
(define $main
(pop! %ktail0) ; [ ret ]
(prim %x1 (call/cc $with-cc)) ; []
(prim %x2 (* 2 %x1)) ; []
(push! %ktail0) ; []
(push! %x2) ; [ ret ]
(tail-call 1) ; [ %x2 ret ]
)
(define $start
(push! $fac) ; [ $start ktail0 ]
(push! 3) ; [ $fac $start ktail0 ]
(tail-call 1) ; [ 3 $fac $start ktail0 ]
;; ↑ `tail-call' knows how to dispose of the caller's stack frame.
)
#+end_src
+4 -4
View File
@@ -70,12 +70,12 @@ pattern ValLabel x = ValImm (ImmLabel x)
newtype Label = MkLabel { inner :: Name }
deriving stock (Generic, Data)
deriving newtype (Show, Eq, Gen, IsString, Hashable)
deriving anyclass (NFData)
deriving anyclass (NFData, Wrapped)
newtype Reg = MkReg { inner :: Name }
deriving stock (Generic, Data)
deriving newtype (Show, Eq, Gen, IsString, Hashable)
deriving anyclass (NFData)
deriving anyclass (NFData, Wrapped)
data Imm
= ImmInt Int
@@ -95,7 +95,7 @@ pattern ObjLabel l = ObjImm (ImmLabel l)
-- | a heap object.
data Hob
= HobClosure { label :: Name, env :: List Obj }
= HobClosure { label :: Label, env :: List Obj }
| HobPair Obj Obj
deriving stock (Show, Generic, Data, Eq)
deriving anyclass (NFData)
@@ -213,7 +213,7 @@ instance S.DatumIso Hob where
where
conspair = S.dottedList (S.el S.datumIso) S.datumIso
-- closures can be printed, but not parsed.
closure :: G (Datum :- t) (List Obj :- Name :- t)
closure :: G (Datum :- t) (List Obj :- Label :- t)
closure = IG.Flip $ IG.PartialIso
(\(env:-code:-t) -> S.Unreadable "#<procedure>" :- t)
(const . Left $ mempty)
+5 -3
View File
@@ -14,7 +14,9 @@ module Gyehoek.Stack.Syntax
, Imm(..)
, Hob(..)
, Prim(..)
, Name
, Name(..)
, Reg(..)
, Label(..)
, pattern ValLabel
, pattern ObjLabel
, stkP
@@ -72,7 +74,7 @@ data Tail
data Instr
= Pop Reg
| Push Val
| Load Reg
| Load Reg Int
| Prim Reg (Prim Val)
deriving stock (Show, Generic, Data)
deriving anyclass (NFData)
@@ -95,7 +97,7 @@ instance S.DatumIso Instr where
datumIso = S.match
$ S.With (S.headTagged1 "pop!" S.datumIso >>>)
$ S.With (S.headTagged1 "push!" S.datumIso >>>)
$ S.With (S.headTagged1 "load!" S.datumIso >>>)
$ S.With (S.headTagged2 "load" S.datumIso S.datumIso >>>)
$ S.With (S.headTagged2 "prim" S.datumIso S.datumIso >>>)
$ S.End
where
+136 -51
View File
@@ -1,4 +1,6 @@
{-# LANGUAGE ViewPatterns, MultilineStrings #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE DeriveAnyClass #-}
module Gyehoek.Stack.VM
( VM(..)
, Env(..)
@@ -28,34 +30,51 @@ import Control.DeepSeq (deepseq, ($!!))
import Gyehoek.Sexp.Print (htmlData, htmlDatum)
import Control.DeepSeq (deepseq, ($!!))
import Data.String (fromString)
import Data.Monoid (First)
import GHC.Stack (popCallStack)
import Data.Maybe (fromMaybe)
-- | non-essential information maintained only to aide in debugging.
data DebugVM = MkDebugVM
{ currentRoutine :: Name
{ activeRoutine :: Label
}
deriving (Show, Generic)
newtype Frame = MkFrame { locals :: List Obj }
deriving (Show, Generic)
deriving stock (Show, Generic)
returnAddress :: Traversal' Frame Name
-- affine
returnAddress :: Traversal' Frame Label
returnAddress = #locals . _last . #ObjImm . #ImmLabel
-- affine
activeProcedure :: Traversal' Frame Label
activeProcedure = #locals . _init . _last . #ObjImm . #ImmLabel
callStack :: Traversal' Stack Label
callStack = each . activeProcedure
newtype Stack = MkStack { frames :: NonEmpty Frame }
deriving (Show, Generic)
deriving stock (Show, Generic)
data VM = MkVM
{ stack :: Stack
, code :: List Instr
, tail :: Tail
, registers :: HashMap Name Obj
, registers :: HashMap Reg Obj
, stdout :: Text
, result :: Maybe (List Obj)
, debug :: DebugVM
}
deriving (Show, Generic)
type instance Index Frame = Int
type instance IxValue Frame = Obj
instance Ixed Frame where
ix j = wrappedIso . ix j
instance Cons Frame Frame Obj Obj where
_Cons = prism'
(\(x,MkFrame xs) -> MkFrame (x:xs))
@@ -63,6 +82,13 @@ instance Cons Frame Frame Obj Obj where
MkFrame (x:xs) -> Just (x, MkFrame xs)
MkFrame [] -> Nothing
instance Each Frame Frame Obj Obj where each = wrappedIso . each
instance Each Stack Stack Frame Frame where each = wrappedIso . each
pushes :: Foldable f => f Obj -> Frame -> Frame
pushes = flip $ foldr cons
_NonEmpty :: Iso (NonEmpty a) (NonEmpty b) (a, List a) (b, List b)
_NonEmpty = iso
(\(x:|xs) -> (x,xs))
@@ -75,7 +101,7 @@ activeFrame :: Lens' VM Frame
activeFrame = #stack . #frames . _NonEmpty . _1
data Env = MkEnv
{ labels :: HashMap Name Routine
{ labels :: HashMap Label Routine
}
deriving (Show, Generic)
@@ -89,6 +115,10 @@ vmerror = throwError . VMError
stepI :: Jalmot :> es => Env -> VM -> Instr -> Eff es VM
stepI e vm (Load r j) = do
x <- expectOf [i|object at index #{j}|] (activeFrame . ix j) vm
pure $ vm & #registers . at r ?~ x
stepI e vm (Push v) = traverseOf activeFrame push vm
where push xs = cons <$> evalVal e vm v <*> pure xs
@@ -135,58 +165,84 @@ stepI e vm ins = vmerror [i|unimplemented instruction: #{ins}|]
stepT :: Jalmot :> es => Env -> VM -> Tail -> Eff es VM
stepT g vm (Return nret) =
case splitAtExact nret (vm ^. activeFrame . #locals) of
Nothing -> _
Just (_,_) -> _
stepT g vm tc@(Call nargs) = do
(args,f,ret,frm) <- parseCall nargs (vm ^. activeFrame)
& expectOf [i|#{show tc}|] _Just
rt <- getRoutine g f
let newFrame = MkFrame $ args ++ [ObjLabel f,ObjLabel ret]
pure $ vm
& jumpToRoutine rt
& activeFrame .~ frm
& #stack %~ pushFrame newFrame
-- it is not essential we clear the registers, but it'll
-- make bugs more obvious.
& #registers .~ mempty
stepT g vm tc@(TailCall nargs) =
case parseTailCall nargs (vm ^. activeFrame) of
Nothing -> vmerror [i|bad stack at #{tc}|]
Just (args,"halt",_) -> pure $ vm & #result ?~ args
Just (args,f,ra) -> do
stepT g vm tc@(Return nret) = do
(xs,_) <- splitAtExact nret (vm ^. activeFrame . #locals)
& expectOf [i|"#{show tc}"|] _Just
expectOf [i||] (activeFrame . returnAddress) vm >>= \case
"halt" -> pure $ vm & #result ?~ xs
ra -> do
rt <- getRoutine g ra
vm & traverseOf #stack (fmap snd . popFrame)
& mapped . activeFrame %~ pushes xs
& mapped %~ jumpToRoutine rt
stepT g vm tc@(TailCall nargs) = do
(args,f,ra) <- parseTailCall nargs (vm ^. activeFrame)
& expectOf [i|#{show tc}|] _Just
case f of
"halt" -> pure $ vm & #result ?~ args
_ -> do
rt <- case g ^. #labels . at f of
Nothing -> vmerror [i|undefined label #{f}|]
Just x -> pure x
let newFrame = MkFrame $ args ++ [ObjLabel f, ObjLabel ra]
pure $ vm
& #code .~ rt.start.code
& #tail .~ rt.start.tail
& jumpToRoutine rt
-- replace the active frame; don't push a new one.
& activeFrame .~ newFrame
-- it is not essential we clear the registers, but it'll
-- make bugs more obvious.
& #registers .~ mempty
-- stepT g vm tc@(TailCall nargs) =
-- case setupCall nargs (vm ^. stack) of
-- Nothing -> vmerror [i|bad stack at #{tc}|]
-- Just (xs,f,rest) ->
-- case f of
-- "halt" -> pure $ vm & #result ?~ xs
-- l -> do
-- rt <- case g ^. #labels . at l of
-- Nothing -> vmerror [i|undefined label: #{l}|]
-- Just x -> pure x
-- let ra = vm ^. #activeFrame . #returnAddress
-- let newFrame = MkFrame $ xs ++ [ObjLabel f, ra]
-- pure $ vm
-- & #code .~ rt.start.code
-- & #tail .~ rt.start.tail
-- & stack .~ rest
-- & #frames %~ NE.cons newFrame
-- -- it is not essential we clear the registers, but it'll
-- -- make bugs more obvious.
-- & #registers .~ mempty
-- & #debug . #currentRoutine .~ rt.label
stepT g vm (If c t f) = do
branch <- evalVal g vm c <&> \case
ObjImm (ImmBool False) -> f
_ -> t
pure $ vm & #code .~ branch.code & #tail .~ branch.tail
pure $ jumpToBlock branch vm
evalToLabel :: Jalmot :> es => Env -> VM -> Val -> Eff es Name
popFrame :: (HasCallStack, Jalmot :> es) => Stack -> Eff es (Frame, Stack)
popFrame stk = case stk ^. #frames . to NE.uncons of
(_, Nothing) -> vmerror "no frame to pop"
(f, Just fs) -> pure (f, stk & #frames .~ fs)
jumpToBlock :: Block -> VM -> VM
jumpToBlock b vm = vm
& #code .~ b.code
& #tail .~ b.tail
jumpToRoutine :: Routine -> VM -> VM
jumpToRoutine rt vm = vm
& jumpToBlock rt.start
& #debug . #activeRoutine .~ rt.label
getRoutine :: (HasCallStack, Jalmot :> es) => Env -> Label -> Eff es Routine
getRoutine g l = case g ^. #labels . at l of
Just rt -> pure rt
Nothing -> vmerror [i|undefined label #{l}|]
expectOf
:: (HasCallStack, Jalmot :> es)
=> Text -> Getting (First a) s a -> s -> Eff es a
expectOf msg l s = case s ^? l of
Just x -> pure x
Nothing -> vmerror [i|bad stack, expecting #{msg}|]
evalToLabel :: Jalmot :> es => Env -> VM -> Val -> Eff es Label
evalToLabel e vm v =
evalVal e vm v >>= \case
ObjImm (ImmLabel x) -> pure x
@@ -209,7 +265,15 @@ takeExact n xs = case compareLength xs n of
(EQ;GT) -> Just $ take n xs
LT -> Nothing
parseTailCall :: Int -> Frame -> Maybe (List Obj, Name, Name)
parseCall :: Int -> Frame -> Maybe (List Obj, Label, Label, Frame)
parseCall nargs frm = do
(xs,ys) <- splitAtExact (nargs+2) (frm ^. #locals)
let (xs',[f,ret]) = splitAt nargs xs
f' <- f ^? #ObjImm . #ImmLabel
ret' <- ret ^? #ObjImm . #ImmLabel
pure (xs',f',ret',MkFrame ys)
parseTailCall :: Int -> Frame -> Maybe (List Obj, Label, Label)
parseTailCall nargs frm = do
(xs,_) <- splitAtExact (nargs+1) (frm ^. #locals)
let (xs',f) = xs ^?! _Snoc
@@ -229,7 +293,7 @@ initialVM = MkVM
, stdout = ""
, result = Nothing
, debug = MkDebugVM
{ currentRoutine = "<nowhere>"
{ activeRoutine = "<nowhere>"
}
}
@@ -329,7 +393,7 @@ ppTrace trace =
table_ do
thead_ $ tr_ do
traverse_ (th_ [scope_ "col"])
["location","instruction","stack"]
["routine","next instruction","stack frame"]
tbody_ do
go trace
where
@@ -361,14 +425,14 @@ ppVM vm = do
td_ do
details_ do
summary_ do
var_ [class_ "loc"] . toHtml $ vm ^. #debug . #currentRoutine
. re (_Unwrapped' . prefixed "$")
var_ [class_ "loc"] do
vm ^. #debug . #activeRoutine . to ppDatum
pre_ do
code_ . toHtml . pShowNoColor $ vm
td_ do
code_ curi
td_ do
let xs = _
let xs = vm ^.. activeFrame . each . to ppDatum
sequence_ $ intersperse " | " xs
where
curi = vm ^?! failing (#code . _head . to ppDatum) (#tail . to ppDatum)
@@ -376,7 +440,28 @@ ppVM vm = do
ppDatum :: S.DatumIso a => a -> Html ()
ppDatum = htmlDatum . runJalmotUnsafe . S.toDatum S.datumIso
blah = [stkP|
(define $start
(return 0))
|]
fac (n :: Int) = [stkP|
(define $start
(push! $fac)
(push! #{n})
(tail-call 1))
(define $fac
(load %n 0)
(prim %x0 (zero? %n))
(if %x0
(then (push! 1)
(return 1))
(else (prim %x1 (- %n 1))
(push! $fac-c0)
(push! $fac)
(push! %x1)
(call 1))))
(define $fac-c0
(pop! %x2)
(pop! %n)
(prim %x3 (* %n %x2))
(push! %x3)
(return 1))
|]
+87 -56
View File
@@ -7,6 +7,7 @@ import Gyehoek.Stack.Syntax
import Gyehoek.Stack.VM qualified as Sut
import Data.List (List)
import Gyehoek.Jalmot
import Gyehoek.Prelude (i)
evalsTo :: List Obj -> Program -> Assertion
@@ -14,7 +15,7 @@ evalsTo rs p = runJalmotUnsafe (Sut.eval p) @?= rs
test_root = testGroup "stack machine"
[ testCase "immediate halt" do
evalsTo [ObjImm (ImmInt 3)] [stkP|
evalsTo [] [stkP|
(define $start
(return 0))
|]
@@ -24,59 +25,89 @@ test_root = testGroup "stack machine"
(push! 3)
(return 1))
|]
-- , testCase "return constant" do
-- evalsTo [ObjImm (ImmInt 123)] [stkP|
-- (define ($start %ktail)
-- (tail-call $silly %ktail))
-- (define ($silly %ktail)
-- (tail-call %ktail 123))
-- |]
-- , testCase "identity continuation" do
-- evalsTo [ObjImm (ImmInt 45)] [stkP|
-- (define ($start %ktail)
-- (push! %ktail)
-- (tail-call $id 45))
-- (define ($id %x)
-- (pop! %ktail)
-- (tail-call %ktail %x))
-- |]
-- , testCase "identity function" do
-- evalsTo [ObjImm (ImmInt 45)] [stkP|
-- (define ($start %ktail)
-- (tail-call $id 45 %ktail))
-- (define ($id %x %ktail)
-- (tail-call %ktail %x))
-- |]
-- , testCase "square" do
-- evalsTo [ObjImm (ImmInt 16)] [stkP|
-- (define ($start %ktail)
-- (tail-call $square 4 %ktail))
-- (define ($square %x %ktail)
-- (prim %x2 (* %x %x))
-- (tail-call %ktail %x2))
-- |]
-- , testCase "factorial" do
-- let hsfac (n :: Int) = foldr (*) (1) [1..n]
-- let fac (n :: Int) = [stkP|
-- (define ($fac %n %ktail)
-- (prim %x0 (zero? %n))
-- (if %x0
-- (then (tail-call %ktail 1))
-- (else (push! %n)
-- (push! %ktail)
-- (prim %x1 (- %n 1))
-- (tail-call $fac %x1 $fac-k0))))
-- (define ($fac-k0 %x2)
-- (pop! %ktail)
-- (pop! %n)
-- (prim %x3 (* %x2 %n))
-- (tail-call %ktail %x3))
-- (define ($start %ktail)
-- (tail-call $fac #{n} %ktail))
-- |]
-- evalsTo [ObjImm (ImmInt 1)] $ fac 0
-- evalsTo [ObjImm (ImmInt 1)] $ fac 1
-- evalsTo [ObjImm (ImmInt 720)] $ fac 6
-- -- 20 is the greatest `n` for which n! ≤ maxBount @Int
-- evalsTo [ObjImm (ImmInt 2432902008176640000)] $ fac 20
, testCase "non-tail identity function" do
evalsTo [ObjImm (ImmInt 123)] [stkP|
(define $id
(return 1))
(define $c
(return 1))
(define $start
(push! $c)
(push! $id)
(push! 123)
(call 1))
|]
, testCase "tail identity function" do
evalsTo [ObjImm (ImmInt 123)] [stkP|
(define $id
(return 1))
(define $start
(push! $id)
(push! 123)
(tail-call 1))
|]
, testCase "return constant" do
evalsTo [ObjImm (ImmInt 123)] [stkP|
(define $start
(push! $silly)
(tail-call 1))
(define $silly
(push! 123)
(return 1))
|]
, testCase "return multiple" do
evalsTo [ObjImm (ImmInt n) | n <- [1,2,3]] [stkP|
(define $start
(push! 3)
(push! 2)
(push! 1)
(return 3))
|]
, testCase "return none" do
evalsTo [] [stkP|
(define $start
(return 0))
|]
, testCase "square" do
evalsTo [ObjImm (ImmInt 16)] [stkP|
(define $start
(push! $square)
(push! 4)
(tail-call 1))
(define $square
(pop! %x)
(prim %x2 (* %x %x))
(push! %x2)
(return 1))
|]
, testGroup "factorial"
let
hsfac (n :: Int) = foldr @List (*) (1) [1..n]
fac (n :: Int) = [stkP|
(define $start
(push! $fac)
(push! #{n})
(tail-call 1))
(define $fac
(load %n 0)
(prim %x0 (zero? %n))
(if %x0
(then (push! 1)
(return 1))
(else (prim %x1 (- %n 1))
(push! $fac-c0)
(push! $fac)
(push! %x1)
(call 1))))
(define $fac-c0
(pop! %x2)
(pop! %n)
(prim %x3 (* %n %x2))
(push! %x3)
(return 1))
|]
mkcase n = testCase [i|#{n}|] do
evalsTo [ObjImm . ImmInt $ hsfac n] $ fac n
-- 20 is the greatest `n` for which n! ≤ maxBount @Int
in [ mkcase n | n <- [0,1,6,20] ]
]