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added docs for performance caveat / fix style
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kailuowang committed Mar 27, 2017
1 parent 51d62ed commit 5b5eea8
Showing 1 changed file with 6 additions and 2 deletions.
8 changes: 6 additions & 2 deletions core/src/main/scala/cats/Monad.scala
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,8 @@ import syntax.either._
* Execute an action repeatedly as long as the given `Boolean` expression
* returns `true`. The condition is evaluated before the loop body.
* Collects the results into an arbitrary `Alternative` value, such as a `Vector`.
* This implementation uses append on each evaluation result,
* so avoid data structures with non-constant append performance, e.g. `List`.
*/
def whileM[G[_], A](p: F[Boolean])(body: => F[A])(implicit G: Alternative[G]): F[G[A]] = {
val b = Eval.later(body)
Expand Down Expand Up @@ -53,6 +55,8 @@ import syntax.either._
* Execute an action repeatedly until the `Boolean` condition returns `true`.
* The condition is evaluated after the loop body. Collects results into an
* arbitrary `Alternative` value, such as a `Vector`.
* This implementation uses append on each evaluation result,
* so avoid data structures with non-constant append performance, e.g. `List`.
*/
def untilM[G[_], A](f: F[A])(cond: => F[Boolean])(implicit G: Alternative[G]): F[G[A]] = {
val p = Eval.later(cond)
Expand All @@ -75,7 +79,7 @@ import syntax.either._
def iterateWhile[A](f: F[A])(p: A => Boolean): F[A] = {
flatMap(f) { i =>
tailRecM(i) { a =>
if(p(a))
if (p(a))
map(f)(_.asLeft[A])
else pure(a.asRight[A])
}
Expand All @@ -89,7 +93,7 @@ import syntax.either._
def iterateUntil[A](f: F[A])(p: A => Boolean): F[A] = {
flatMap(f) { i =>
tailRecM(i) { a =>
if(p(a))
if (p(a))
pure(a.asRight[A])
else map(f)(_.asLeft[A])
}
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