search

cloudRoutine / issueCommRepo

Sample Port of F# Uservoice Suggestions
0 stars 0 forks source link

Pattern matching on member defintions #37

Closed cloudRoutine closed 7 years ago

cloudRoutine commented 7 years ago

Pattern matching on member defintions [11699604]

Submitted by Harald Steinlechner on 2/3/2016 12:00:00 AM
[ 1 votes ]

when extending discriminated unions with member implementations we can introduce a fresh name for 'this' (usually this or x). This identifier however is syntactically not a pattern. It would be nice (for irrefutable patterns) to match directly on this position, .e.g.: type Test2 = Test2 of int * int with member (Test(a,b)).Blub() = a + b instead of: type Test = Test of int * int with member x.Blub() = let (Test(a,b)) = x in a + b The benefit seems to be minor, but additionally my proposal improves uniformity of the language. However i fear this introduces ambiguities in the parser....

Response

\ by fslang-admin on 2/3/2016 12:00:00 AM **

Declined – see comment above Don Syme, F# Language Evolution

cloudRoutine commented 7 years ago

Posted by Don Syme on 2/3/2016 10:21:00 AM

Hi Harald, Thanks for taking the time to write this suggestion. We considered this in the F# design, but decided against it since we felt that code became substantially less readable when this formulation was used. I don't think we'll revisit the design decision at this point. Best Don Syme, F# Language Evolution