Higher Kinded Types (WIP) #1
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jroesch
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Dec 16, 2014
…ariables Diagnostics such as the following ``` mismatched types: expected `core::result::Result<uint,()>`, found `core::option::Option<<generic #1>>` <anon>:6 let a: Result<uint, ()> = None; ^~~~ mismatched types: expected `&mut <generic #2>`, found `uint` <anon>:7 f(42u); ^~~ ``` tend to be fairly unappealing to new users. While specific type var IDs are valuable in diagnostics that deal with more than one such variable, in practice many messages only mention one. In those cases, leaving out the specific number makes the messages slightly less terrifying. In addition, type variables have been changed to use the type hole syntax `_` in diagnostics. With a variable ID, they're printed as `_#id` (e.g. `_#1`). In cases where the ID is left out, it's simply `_`. Integer and float variables have an additional suffix after the number, e.g. `_#1i` or `_#3f`.
jroesch
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Dec 16, 2014
…, r=nikomatsakis This PR aims to improve the readability of diagnostic messages that involve unresolved type variables. Currently, messages like the following: ```rust mismatched types: expected `core::result::Result<uint,()>`, found `core::option::Option<<generic #1>>` <anon>:6 let a: Result<uint, ()> = None; ^~~~ mismatched types: expected `&mut <generic #2>`, found `uint` <anon>:7 f(42u); ^~~ ``` tend to appear unapproachable to new users. [0] While specific type var IDs are valuable in diagnostics that deal with more than one such variable, in practice many messages only mention one. In those cases, leaving out the specific number makes the messages slightly less terrifying. ```rust mismatched types: expected `core::result::Result<uint, ()>`, found `core::option::Option<_>` <anon>:6 let a: Result<uint, ()> = None; ^~~~ mismatched types: expected `&mut _`, found `uint` <anon>:7 f(42u); ^~~ ``` As you can see, I also tweaked the aesthetics slightly by changing type variables to use the type hole syntax _. For integer variables, the syntax used is: ```rust mismatched types: expected `core::result::Result<uint, ()>`, found `core::option::Option<_#1i>` <anon>:6 let a: Result<uint, ()> = Some(1); ``` and float variables: ```rust mismatched types: expected `core::result::Result<uint, ()>`, found `core::option::Option<_#1f>` <anon>:6 let a: Result<uint, ()> = Some(0.5); ``` [0] https://twitter.com/coda/status/517713085465772032 Closes rust-lang#2632. Closes rust-lang#3404. Closes rust-lang#18426.
jroesch
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Jan 2, 2015
Fixes rust-lang#19707. In terms of output, it currently uses the form `argument #1`, `argument #2`, etc. If anyone has any better suggestions I would be glad to consider them.
jroesch
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Dec 4, 2015
…hange Change verbiage in Stack & Heap page
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My initial attempts to figuring out how higher kinded types would work in Rust.
Note: For any interested parties I have an RFC in the works as well, just wanted to get my hands into the type checker while writing it, will be making updates as I can.