From 93b2ddfc88f581a1155236c9ac79983f72b0ff46 Mon Sep 17 00:00:00 2001 From: Alexei Sholik Date: Sat, 8 Jun 2013 04:02:41 +0300 Subject: [PATCH] A reminder that a block is a single expr in closures This is something that's only been briefly mentioned in the beginning of the tutorial and all of the closure examples within this subsection include only one expression between { and }. --- doc/tutorial.md | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/doc/tutorial.md b/doc/tutorial.md index 8caf8704e0589..0066434c40cc0 100644 --- a/doc/tutorial.md +++ b/doc/tutorial.md @@ -1439,10 +1439,15 @@ call_closure_with_ten(closure); ~~~~ Closures begin with the argument list between vertical bars and are followed by -a single expression. The types of the arguments are generally omitted, -as is the return type, because the compiler can almost always infer -them. In the rare case where the compiler needs assistance, though, the -arguments and return types may be annotated. +a single expression. Remember that a block, `{ ; ; ... }`, is +considered a single expression: it evaluates to the result of the last +expression it contains if that expression is not followed by a semicolon, +otherwise the block evaluates to `()`. + +The types of the arguments are generally omitted, as is the return type, +because the compiler can almost always infer them. In the rare case where the +compiler needs assistance, though, the arguments and return types may be +annotated. ~~~~ let square = |x: int| -> uint { x * x as uint };