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https://github.com/lue-bird/elm-review-equals-caseable
elm-review: report `==` when equivalent `case of` exists
https://github.com/lue-bird/elm-review-equals-caseable
case-of elm elm-review equal if match
Last synced: 22 days ago
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elm-review: report `==` when equivalent `case of` exists
- Host: GitHub
- URL: https://github.com/lue-bird/elm-review-equals-caseable
- Owner: lue-bird
- License: mit
- Created: 2023-07-19T21:31:01.000Z (over 1 year ago)
- Default Branch: main
- Last Pushed: 2023-07-21T11:00:04.000Z (over 1 year ago)
- Last Synced: 2024-12-09T18:02:07.193Z (26 days ago)
- Topics: case-of, elm, elm-review, equal, if, match
- Language: Elm
- Homepage: https://dark.elm.dmy.fr/packages/lue-bird/elm-review-equals-caseable/latest/
- Size: 115 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# [elm-review-equals-caseable](https://dark.elm.dmy.fr/packages/lue-bird/elm-review-equals-caseable/latest/)
Provides the [`elm-review`](https://package.elm-lang.org/packages/jfmengels/elm-review/latest/) rule [🔧`EqualsCaseable.forbid`](https://package.elm-lang.org/packages/lue-bird/elm-review-equals-caseable/1.0.0/EqualsCaseable#forbid) which reports when `==` is used but there's an equivalent `case of` available.
## reported
```elm
a =
if list == [] then
"empty"
else
"filled"
```
## not reported
```elm
a =
case list of
[] ->
"empty"
_ :: _ ->
"filled"
```
## why
Reasons are pretty similar to [`VariablesBetweenCaseOf.AccessInCases.forbid`](https://dark.elm.dmy.fr/packages/lue-bird/elm-review-variables-between-case-of-access-in-cases/latest/#why).
Let me highlight the most important ones:
(Note: The exhaustiveness benefits shown are possible once [`NoWildcard`](https://github.com/jfmengels/elm-review/discussions/91) is implemented.)
### notifies you when adding a new variant
```elm
type Role
= Admin
| User
canBanUser =
\theUserWhoTriesToBan -> theUserWhoTriesToBan.role == Admin
```
It's a new day and time for a new feature: moderators!
```elm
type Role
= Admin
| Moderator
| User
```
> It compiles, so it works! Time for a break.
☕
> Oh crap! It don't work I'm sad elm has failed me I'm going back to typescript.
Oh no, you made them sad.
With the rules enabled:
```elm
type Role
= Admin
| User
canBanUser =
\theUserWhoTriesToBan -> theUserWhoTriesToBan.role == Admin
```
→ `EqualsCaseable.forbid Everywhere` fixes to
```elm
canBanUser =
\theUserWhoTriesToBan ->
case theUserWhoTriesToBan.role of
Admin ->
True
_ ->
False
```
→ `NoWildcard.rule` fixes to
```elm
canBanUser =
\theUserWhoTriesToBan ->
case theUserWhoTriesToBan.role of
Admin ->
True
User ->
False
```
Now if you add moderator, elm will show you where there's more to handle specifically for moderators. Or as a quote by @janiczek on slack
> Now the compiler will tell me all the places I need to make a new decision
### gives the compiler as much information as you have
Here's [a real example](https://github.com/dillonkearns/elm-pages/blob/9d6d30235f7db8d3c2c0b40d78f3cc5a6278562d/src/Pages/Internal/RoutePattern.elm#L418)
```elm
toVariant pattern =
if ... pattern.ending == Nothing then
Elm.variant "Index"
else
let
allSegments =
...
++ ([ Maybe.map endingToVariantName pattern.ending
]
|> List.filterMap identity
)
in
...
```
Don't do this to yourself. Let the compiler know as much as you about the path you're in.
```elm
toVariant pattern =
case pattern.ending of
Nothing ->
Elm.variant "Index"
Just patternEnding ->
let
allSegments =
... ++ [ endingToVariantName patternEnding ]
in
...
```
### doesn't make you jump around
Here's [a real example](https://github.com/dillonkearns/elm-pages/blob/9d6d30235f7db8d3c2c0b40d78f3cc5a6278562d/src/Pages/Internal/Platform.elm#L941)
```elm
if fields.method == Form.Get then
model.key
|> Maybe.map
(\key ->
Browser.Navigation.pushUrl key
(appendFormQueryParams fields)
)
|> Maybe.withDefault
Cmd.none
else
-- wait, ... What is else?
let
urlToSubmitTo : Url
urlToSubmitTo =
model.url
in
fetchRouteData -1
(UpdateCacheAndUrlNew False model.url Nothing)
config
urlToSubmitTo
(Just fields)
```
be explicit :)
```elm
case fields.method of
Form.Get ->
model.key
|> Maybe.map
(\key ->
Browser.Navigation.pushUrl key
(appendFormQueryParams fields)
)
|> Maybe.withDefault
Cmd.none
Form.Post ->
let
urlToSubmitTo : Url
urlToSubmitTo =
model.url
in
fetchRouteData -1
(UpdateCacheAndUrlNew False model.url Nothing)
config
urlToSubmitTo
(Just fields)
```
## try it out
You can try the example configuration above out by running the following command:
```bash
elm-review --template lue-bird/elm-review-equals-caseable/example
```
## configure
```elm
module ReviewConfig exposing (config)
import EqualsCaseable
import Review.Rule exposing (Rule)
config : List Rule
config =
[ EqualsCaseable.forbid EqualsCaseable.InIf
]
```