Specify refutability of patterns in let and if let #660
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Centril
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Aug 28, 2019
src/expressions/if-expr.md
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| pattern, an `=` and a [scrutinee] expression. If the value of the scrutinee | ||
| matches the pattern, the corresponding block will execute. Otherwise, flow | ||
| proceeds to the following `else` block if it exists. Like `if` expressions, | ||
| refutable pattern, an `=` and a [scrutinee] expression. If the value of the |
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The pattern in if let can be irrefutable.
|
Of course! Sorry. I misunderstood the definition of refutable to encompass
irrefutable. If I may that change, is this a fix to which you are open?
…On Wed, Aug 28, 2019, 4:53 AM Mazdak Farrokhzad ***@***.***> wrote:
***@***.**** commented on this pull request.
------------------------------
In src/expressions/if-expr.md
<#660 (comment)>
:
> @@ -53,9 +53,9 @@ assert_eq!(y, "Bigger");
An `if let` expression is semantically similar to an `if` expression but in
place of a condition expression it expects the keyword `let` followed by a
-pattern, an `=` and a [scrutinee] expression. If the value of the scrutinee
-matches the pattern, the corresponding block will execute. Otherwise, flow
-proceeds to the following `else` block if it exists. Like `if` expressions,
+refutable pattern, an `=` and a [scrutinee] expression. If the value of the
The pattern in if let can be irrefutable.
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<#660>,
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|
|
This appears to contradict:
https://doc.rust-lang.org/book/ch18-02-refutability.html
…On Wed, Aug 28, 2019, 5:47 AM Will Hawkins ***@***.***> wrote:
Of course! Sorry. I misunderstood the definition of refutable to encompass
irrefutable. If I may that change, is this a fix to which you are open?
On Wed, Aug 28, 2019, 4:53 AM Mazdak Farrokhzad ***@***.***>
wrote:
> ***@***.**** commented on this pull request.
> ------------------------------
>
> In src/expressions/if-expr.md
> <#660 (comment)>
> :
>
> > @@ -53,9 +53,9 @@ assert_eq!(y, "Bigger");
>
> An `if let` expression is semantically similar to an `if` expression but in
> place of a condition expression it expects the keyword `let` followed by a
> -pattern, an `=` and a [scrutinee] expression. If the value of the scrutinee
> -matches the pattern, the corresponding block will execute. Otherwise, flow
> -proceeds to the following `else` block if it exists. Like `if` expressions,
> +refutable pattern, an `=` and a [scrutinee] expression. If the value of the
>
> The pattern in if let can be irrefutable.
>
> —
> You are receiving this because you authored the thread.
> Reply to this email directly, view it on GitHub
> <#660>,
> or mute the thread
> <https://github.com/notifications/unsubscribe-auth/ACCP2CT2AXDMSK3KPDIE7QDQGY4J3ANCNFSM4IQ7VDRA>
> .
>
|
The book is wrong. |
|
Ok. Should we reconcile the two?
…On Wed, Aug 28, 2019, 6:14 AM Mazdak Farrokhzad ***@***.***> wrote:
This appears to contradict:
https://doc.rust-lang.org/book/ch18-02-refutability.html
The book is wrong.
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<#660>,
or mute the thread
<https://github.com/notifications/unsubscribe-auth/ACCP2CS7U7V3LOF7JOPGF2TQGZFXXANCNFSM4IQ7VDRA>
.
|
|
Thanks for working on this with me!
…On Wed, Aug 28, 2019, 6:15 AM Will Hawkins ***@***.***> wrote:
Ok. Should we reconcile the two?
On Wed, Aug 28, 2019, 6:14 AM Mazdak Farrokhzad ***@***.***>
wrote:
> This appears to contradict:
> https://doc.rust-lang.org/book/ch18-02-refutability.html
>
> The book is wrong.
>
> —
> You are receiving this because you authored the thread.
> Reply to this email directly, view it on GitHub
> <#660>,
> or mute the thread
> <https://github.com/notifications/unsubscribe-auth/ACCP2CS7U7V3LOF7JOPGF2TQGZFXXANCNFSM4IQ7VDRA>
> .
>
|
|
Yes we should. Please file a bug against the book's repo. |
|
Corresponds to rust-lang/book#2039 which updates the Book. I hope that this is a helpful PR. @Centril |
Specify that patterns in 1. 'if let' and 'while let' expressions are either refutable or irrefutable 2. 'let' and 'for' statements are always irrefutable
|
Closing to reopen because I am expanding the scope slightly. |
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Specify that patterns in 'if let' expressions are refutable
while patterns in 'let' statements are irrefutable.