From eef1cb2a691362585e15db59b778075e51a54c2f Mon Sep 17 00:00:00 2001
From: Folkert <folkert@folkertdev.nl>
Date: Fri, 19 Mar 2021 00:27:34 +0100
Subject: [PATCH] use multi-backpassing in base64 example

---
 compiler/parse/src/expr.rs            |  2 +
 examples/benchmarks/Base64/Decode.roc | 60 ++++++++++++---------------
 2 files changed, 29 insertions(+), 33 deletions(-)

diff --git a/compiler/parse/src/expr.rs b/compiler/parse/src/expr.rs
index 4986fbb6d6..6e34bfdf70 100644
--- a/compiler/parse/src/expr.rs
+++ b/compiler/parse/src/expr.rs
@@ -1224,6 +1224,8 @@ fn parse_expr_end<'a>(
                         match word2(b'<', b'-', EExpr::BackpassArrow).parse(arena, state) {
                             Err((_, fail, state)) => Err((MadeProgress, fail, state)),
                             Ok((_, _, state)) => {
+                                let min_indent = start.col;
+
                                 let parse_body = space0_before_e(
                                     move |a, s| parse_loc_expr(min_indent + 1, a, s),
                                     min_indent,
diff --git a/examples/benchmarks/Base64/Decode.roc b/examples/benchmarks/Base64/Decode.roc
index beb0d46077..71d33e6ba9 100644
--- a/examples/benchmarks/Base64/Decode.roc
+++ b/examples/benchmarks/Base64/Decode.roc
@@ -11,47 +11,41 @@ decodeBase64 = \width -> Bytes.Decode.loop loopHelp { remaining: width, string:
 loopHelp : { remaining : Nat, string : Str } -> Decoder (Bytes.Decode.Step { remaining : Nat, string : Str } Str)
 loopHelp = \{ remaining, string } ->
     if remaining >= 3 then
-        Bytes.Decode.map3
-            Bytes.Decode.u8
-            Bytes.Decode.u8
-            Bytes.Decode.u8
-            \x, y, z ->
-                a : U32
-                a = Num.intCast x
-                b : U32
-                b = Num.intCast y
-                c : U32
-                c = Num.intCast z
-                combined = Num.bitwiseOr (Num.bitwiseOr (Num.shiftLeftBy 16 a) (Num.shiftLeftBy 8 b)) c
-                Loop
-                    {
-                        remaining: remaining - 3,
-                        string: Str.concat string (bitsToChars combined 0)
-                    }
+        x, y, z <- Bytes.Decode.map3 Bytes.Decode.u8 Bytes.Decode.u8 Bytes.Decode.u8
+
+        a : U32
+        a = Num.intCast x
+        b : U32
+        b = Num.intCast y
+        c : U32
+        c = Num.intCast z
+        combined = Num.bitwiseOr (Num.bitwiseOr (Num.shiftLeftBy 16 a) (Num.shiftLeftBy 8 b)) c
+        Loop
+            {
+                remaining: remaining - 3,
+                string: Str.concat string (bitsToChars combined 0)
+            }
 
     else if remaining == 0 then
         Bytes.Decode.succeed (Done string)
 
     else if remaining == 2 then
-        Bytes.Decode.map2
-            Bytes.Decode.u8
-            Bytes.Decode.u8
-            \x, y ->
-                a : U32
-                a = Num.intCast x
-                b : U32
-                b = Num.intCast y
-                combined = Num.bitwiseOr (Num.shiftLeftBy 16 a) (Num.shiftLeftBy 8 b)
-                Done (Str.concat string (bitsToChars combined 1))
+        x, y <- Bytes.Decode.map2 Bytes.Decode.u8 Bytes.Decode.u8
+
+        a : U32
+        a = Num.intCast x
+        b : U32
+        b = Num.intCast y
+        combined = Num.bitwiseOr (Num.shiftLeftBy 16 a) (Num.shiftLeftBy 8 b)
+        Done (Str.concat string (bitsToChars combined 1))
 
     else
         # remaining = 1
-        Bytes.Decode.map
-            Bytes.Decode.u8
-            \x ->
-                a : U32
-                a = Num.intCast x
-                Done (Str.concat string (bitsToChars (Num.shiftLeftBy 16 a) 2))
+        x <- Bytes.Decode.map Bytes.Decode.u8
+
+        a : U32
+        a = Num.intCast x
+        Done (Str.concat string (bitsToChars (Num.shiftLeftBy 16 a) 2))
 
 
 bitsToChars : U32, Int * -> Str