From 36241ec290994e4338687647a17711aefc87dbbf Mon Sep 17 00:00:00 2001
From: Manos Koukoutos <emmanouil.koukoutos@epfl.ch>
Date: Fri, 8 May 2015 14:54:51 +0200
Subject: [PATCH] foldr/ scanr signature consistent with Scala
---
library/collection/List.scala | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/library/collection/List.scala b/library/collection/List.scala
index ae282627a..8ae15c41d 100644
--- a/library/collection/List.scala
+++ b/library/collection/List.scala
@@ -327,9 +327,9 @@ sealed abstract class List[T] {
case Cons(h,t) => t.foldLeft(f(z,h))(f)
}
- def foldRight[R](f: (T,R) => R)(z: R): R = this match {
+ def foldRight[R](z: R)(f: (T,R) => R): R = this match {
case Nil() => z
- case Cons(h, t) => f(h, t.foldRight(f)(z))
+ case Cons(h, t) => f(h, t.foldRight(z)(f))
}
def scanLeft[R](z: R)(f: (R,T) => R): List[R] = this match {
@@ -337,10 +337,10 @@ sealed abstract class List[T] {
case Cons(h,t) => z :: t.scanLeft(f(z,h))(f)
}
- def scanRight[R](f: (T,R) => R)(z: R): List[R] = { this match {
+ def scanRight[R](z: R)(f: (T,R) => R): List[R] = { this match {
case Nil() => z :: Nil[R]()
case Cons(h, t) =>
- val rest@Cons(h1,_) = t.scanRight(f)(z)
+ val rest@Cons(h1,_) = t.scanRight(z)(f)
f(h, h1) :: rest
}} ensuring { !_.isEmpty }
@@ -525,7 +525,7 @@ object ListSpecs {
@induct
def scanVsFoldRight[A,B](l: List[A], z: B, f: (A,B) => B): Boolean = {
- l.scanRight(f)(z).head == l.foldRight(f)(z)
+ l.scanRight(z)(f).head == l.foldRight(z)(f)
}.holds
}
--
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