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> On Feb 28, 2017, at 2:17 PM, Erica Sadun <[email protected]> wrote: > > >> On Feb 28, 2017, at 12:19 PM, Matthew Johnson <[email protected]> wrote: >> >> --Apple-Mail=_99FCC835-0665-499E-84F7-EB04BAEF8812 >> Content-Transfer-Encoding: quoted-printable >> Content-Type: text/plain; >> charset=utf-8 >> >> I agree that the ambiguity created by moving `let` outside the local = >> binding context is problematic. I alway place `let` immediately = >> alongside the binding for this reason. =20 >> >> In design 2 do you disallow matching a value using an existing name? If = >> so, how do users match values bound to an existing name? Or is that = >> just not possible? I would oppose design 2 if it=E2=80=99s not = >> possible. > > It shadows, just like it currently does In that case I oppose design 2. If we're going to change this let's fix it and remove the ambiguity (from a reader's perspective when they don't know the rule). > >> Both syntax designs you propose are very concise, but they look like an = >> operator which can take any value with the appropriate type on the left = >> hand side. Unfortunately this isn=E2=80=99t the case (haha). I think = >> that is problematic. Did you consider this? If so, what is the = >> rationale for this choice? >> >> For example, a user might expect to be able to say: >> >> // match is a boolean that is true if the pattern matched and fast = >> otherwise >> let match =3D .success(let value) ~=3D result >> >> // we don=E2=80=99t know if `value` is bound here so we cannot allow the = >> above to be valid code. > > Swift doesn't allow the results of conditional binding to be used as > straightforward > Booleans as they must be bound into a scope. `guard` cheats. I understand that. What I'm saying is that I can't think of any other binary operator in Swift whose result cannot be assigned to a name. For that reason I am not convinced we should adopt the syntax you propose. This *is not* a normal binary operator expression so it shouldn't look like one. > > -- E > > >> >> href=3D"mailto:[email protected]"; = >> class=3D"">[email protected]</a><br = >> class=3D"">https://lists.swift.org/mailman/listinfo/swift-evolution<br = >> class=3D""></div></blockquote></div><br = >> class=3D""></div></div></div></body></html>= >> >> --Apple-Mail=_99FCC835-0665-499E-84F7-EB04BAEF8812-- > _______________________________________________ swift-evolution mailing list [email protected] https://lists.swift.org/mailman/listinfo/swift-evolution
