Add 0.5 docs #3579
Merged
Add 0.5 docs #3579
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
smarter
reviewed
Nov 28, 2017
|
|
||
| (k: Keyed) => k.Key | ||
|
|
||
| This type describes function values that take an argument `x` of type |
There was a problem hiding this comment.
It's k, not x (same on the next line)
There was a problem hiding this comment.
No, k is the parameter. I wanted to use a different name for the argument.
smarter
reviewed
Nov 28, 2017
| A dependent function type describes functions where the result type may depend | ||
| on the function's parameter values. Example: | ||
|
|
||
| class Keyed { type Key; key: Key } |
There was a problem hiding this comment.
Keyed and Key are a bit too easy to confuse when following the example. I would maybe replace Keyed by Entry.
|
|
||
| This query would now be classified as ambiguous. This makes sense, after all | ||
| there are two possible solutions, `b(a1)` and `b(a2)`, neither of which is better | ||
| than the other and both of which are better than the third solution, `c`. |
There was a problem hiding this comment.
Why are b(a1) and b(a2) better than c?
There was a problem hiding this comment.
because their return type is a subtype is of the return type of c
| and the query `implicitly[C]`. | ||
|
|
||
| This query would now be classified as ambiguous. This makes sense, after all | ||
| there are two possible solutions, `b(a1)` and `b(a2)`, neither of which is better |
| type refers to some of the parameters of the method. Method | ||
| `extractKey` is an example. Its result type, `k.key` refers its | ||
| parameter `k` (we also say, `k.Key` _depends_ on `k`). But so far it | ||
| was not possible to turn such methods into function values, so thay |
| def apply(x1: K1, ..., xN: KN): R | ||
| } | ||
|
|
||
| where the result type parameter `R` is an upper approximation of the |
They do not work in code, which is where we would have needed them.
| @@ -0,0 +1,50 @@ | |||
| --- | |||
| layout: doc-page`% | |||
| title: "Dependent`% Function Types" | |||
jvican
reviewed
Nov 29, 2017
| there are two possible solutions, `b(a1)` and `b(a2)`, neither of which is better | ||
| than the other and both of which are better than the third solution, `c`. | ||
| By contrast, Scala 2 would have rejected the search for `A` as | ||
| ambiguous, and subsequently have classified the query `b(implictly[A])` as a normal fail, |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
No description provided.