Add compiler-warning when using mutable or ref

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Add compiler-warning when using mutable or ref [10011624]

Submitted by Wael on 10/1/2015 12:00:00 AM
[ 7 votes ]

add compiler flag: --warn-mutable, --warn-ref which would generate warning when using mutable (either mutable keyword or when using ref). This would allow pure modules to be made. Note that F# doesn't have any "pure" tags on member methods like the "const" qualifier on C++ methods.

Response

\ by fslang-admin on 1/23/2016 12:00:00 AM **

See comment above. Declined since we’d prefer this to be implemented in tools such as FSharpLint. Don Syme, F# Language and Core Library Evolution

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Posted by Radek Micek on 10/19/2015 2:57:00 PM

This would allow pure modules to be made. I don't see how it helps since you can still use some type from referenced assembly which is equivalent to ref. BTW this can be implemented in linter (eg. VFPT).

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Posted by knocte on 1/22/2016 4:26:00 AM

FYI I suggested something similar to this in a comment to this other idea: /archive/suggestion-5670335-pure-functions-pure-keyword NOTE: you can still use mutable locals (as oppoosed to fields), in immutable code (because local vars in a method cannot be shared among threads).

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Posted by Don Syme on 1/23/2016 11:52:00 AM

I would prefer if this were implemented in FSharpLint. I will decline this for the core language and please add a suggestion there, if it isn't available already.