From 24f54b8dcc5f5eda573f23a42e9dfda593cddb9f Mon Sep 17 00:00:00 2001 From: Eli Barzilay Date: Mon, 23 Jun 2008 04:36:05 +0000 Subject: [PATCH] document lazy restriction, try to improve description a little. svn: r10418 --- collects/scribblings/reference/promise.scrbl | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/collects/scribblings/reference/promise.scrbl b/collects/scribblings/reference/promise.scrbl index c73ab04cfe..d8c2af3254 100644 --- a/collects/scribblings/reference/promise.scrbl +++ b/collects/scribblings/reference/promise.scrbl @@ -25,7 +25,11 @@ to produce its value.} @defform[(lazy expr)]{ Like @scheme[delay], except that if @scheme[expr] produces a promise, -then the promise is @scheme[force]d to obtain a value.} +then this promise is @scheme[force]d to obtain a value. In other +words, this form creates a kind of a composable promise, which is +mostly useful for implementing lazy libraries and languages. Also +note that the @scheme[expr] in this case is restricted to one that +produces a single value.} @defproc[(force [v any/c]) any]{