From 741a3b25d603dfc1814a8003f0c1284e1521a1f3 Mon Sep 17 00:00:00 2001
From: Timothy Clem <timothy.clem@gmail.com>
Date: Thu, 20 Sep 2018 09:42:55 -0700
Subject: [PATCH] Implement doWhile in terms of the new while effect

---
 src/Control/Abstract/Value.hs | 44 +++++++++--------------------------
 1 file changed, 11 insertions(+), 33 deletions(-)

diff --git a/src/Control/Abstract/Value.hs b/src/Control/Abstract/Value.hs
index b26de11a4..9018a8370 100644
--- a/src/Control/Abstract/Value.hs
+++ b/src/Control/Abstract/Value.hs
@@ -111,44 +111,22 @@ while :: Member (While value) effects
 while (Evaluator cond) (Evaluator body) = send (While cond body)
 
 -- | Do-while loop, built on top of while.
-doWhile :: (AbstractValue address value effects, Member (Boolean value) effects)
-        => Evaluator address value effects value
-        -> Evaluator address value effects value
-        -> Evaluator address value effects value
-doWhile body cond = undefined
+doWhile :: Member (While value) effects
+  => Evaluator address value effects value
+  -> Evaluator address value effects value
+  -> Evaluator address value effects value
+doWhile body cond = body *> while cond body
 
 -- | C-style for loops.
-forLoop :: ( AbstractValue address value effects
-           , Member (Boolean value) effects
-           , Member (While value) effects
-           , Member (Env address) effects
-           )
-        => Evaluator address value effects value -- ^ Initial statement
-        -> Evaluator address value effects value -- ^ Condition
-        -> Evaluator address value effects value -- ^ Increment/stepper
-        -> Evaluator address value effects value -- ^ Body
-        -> Evaluator address value effects value
+forLoop :: (Member (While value) effects, Member (Env address) effects)
+  => Evaluator address value effects value -- ^ Initial statement
+  -> Evaluator address value effects value -- ^ Condition
+  -> Evaluator address value effects value -- ^ Increment/stepper
+  -> Evaluator address value effects value -- ^ Body
+  -> Evaluator address value effects value
 forLoop initial cond step body =
   locally (initial *> while cond (body *> step))
 
--- -- | The fundamental looping primitive, built on top of 'ifthenelse'.
--- while :: (AbstractValue address value effects, Member (Boolean value) effects)
---       => Evaluator address value effects value
---       -> Evaluator address value effects value
---       -> Evaluator address value effects value
--- while cond body = loop $ \ continue -> do
---   this <- cond
---   ifthenelse this (body *> continue) (pure unit)
---
--- -- | Do-while loop, built on top of while.
--- doWhile :: (AbstractValue address value effects, Member (Boolean value) effects)
---         => Evaluator address value effects value
---         -> Evaluator address value effects value
---         -> Evaluator address value effects value
--- doWhile body cond = loop $ \ continue -> body *> do
---   this <- cond
---   ifthenelse this continue (pure unit)
-
 data While value m result where
   While :: m value -> m value -> While value m value