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Add symbols to FAQ #1573

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Add symbols to FAQ #1573

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07fa107
Add symbols to FAQ
zainab-ali Mar 25, 2017
400555b
Correct location of inject symbols
zainab-ali Apr 9, 2017
71badbf
Merge branch 'master' of https://github.com/typelevel/cats
zainab-ali May 3, 2017
d3b6dd8
Add nicknames
zainab-ali May 3, 2017
84fa9c6
Use html to render pipes within markdown
zainab-ali May 5, 2017
64b8393
Add arrow symbols
zainab-ali May 9, 2017
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35 changes: 35 additions & 0 deletions docs/src/main/tut/faq.md
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Expand Up @@ -21,6 +21,7 @@ position: 4
* [What do types like `?` and `λ` mean?](#kind-projector)
* [What does `macro Ops` do? What is `cats.macros.Ops`?](#machinist)
* [What is `tailRecM`?](#tailrecm)
* [What does this symbol mean?](#symbol)
* [How can I help?](#contributing)

## <a id="what-imports" href="#what-imports"></a>What imports do I need?
Expand Down Expand Up @@ -202,6 +203,40 @@ If you're having trouble figuring out how to implement `tailRecM` lawfully, you

In some cases you may decide that providing a lawful `tailRecM` may be impractical or even impossible (if so we'd like to hear about it). For these cases we provide a way of testing all of the monad laws _except_ for the stack safety of `tailRecM`: just replace `MonadTests[F].monad[A, B, C]` in your tests with `MonadTests[F].stackUnsafeMonad[A, B, C]`.


## <a id="symbol" href="#symbol"></a>What does this symbol mean?

Below is a list of symbols used in cats.

The `~>`, `⊥`, `⊤`, `:<:` and `:≺:` symbols can be imported with `import cats._`.

All other symbols can be imported with `import cats.implicits._`

| Symbol | Name | Nickname | Type Class | Signature |
| -------------------------------- | ---------------------- | ---------------- | ----------------------- | --------------------------------------------------------- |
| <code>fa &#124;@&#124; fb</code> | Cartesian builder | Cinnabon, scream | `Cartesian[F[_]]` | <code>&#124;@&#124;(fa: F[A])(fb: F[B]): F[(A, B)]</code> |
| `fa *> fb` | right apply | | `Cartesian[F[_]]` | `*>(fa: F[A])(fb: F[B]): F[A]` |
| `fa <* fb` | left apply | | `Cartesian[F[_]]` | `<*(fa: F[A])(fb: F[B]): F[B]` |
| `x === y` | equals | | `Eq[A]` | `eqv(x: A, y: A): Boolean` |
| `x =!= y` | not equals | | `Eq[A]` | `neqv(x: A, y: A): Boolean` |
| `fa >>= f` | flatMap | | `FlatMap[F[_]]` | `flatMap(fa: F[A])(f: A => F[B]): F[B]` |
| `fa >> fb` | followed by | | `FlatMap[F[_]]` | `followedBy(fa: F[A])(fb: F[B]): F[B]` |
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As of #1537 there is also << (FlatMap#forEffect).

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I've now added that

| `fa << fb` | for effect | | `FlatMap[F[_]]` | `forEffect(fa: F[A])(fb: F[B]): F[A]` |
| <code>x &#124;-&#124; y</code> | remove | | `Group[A]` | `remove(x: A, y: A): A` |
| `x > y` | greater than | | `PartialOrder[A]` | `gt(x: A, y: A): Boolean` |
| `x >= y` | greater than or equal | | `PartialOrder[A]` | `gteq(x: A, y: A): Boolean` |
| `x < y` | less than | | `PartialOrder[A]` | `lt(x: A, y: A): Boolean` |
| `x <= y` | less than or equal | | `PartialOrder[A]` | `lteq(x: A, y: A): Boolean` |
| <code>x &#124;+&#124; y</code> | Semigroup combine | | `Semigroup[A]` | `combine(x: A, y: A): A` |
| `x <+> y` | SemigroupK combine | | `SemigroupK[F[_]]` | `combineK(x: F[A], y: F[A]): F[A]` |
| `f <<< g` | Arrow compose | | `Compose[F[_, _]]` | `compose(f: F[B, C], g: F[A, B]): F[A, C]` |
| `f >>> g` | Arrow andThen | | `Compose[F[_, _]]` | `andThen(f: F[B, C], g: F[A, B]): F[A, C]` |
| `F ~> G` | natural transformation | | `FunctionK[F[_], G[_]]` | `FunctionK` alias |
| `F :<: G` | injectK | | `InjectK[F[_], G[_]]` | `InjectK` alias |
| `F :≺: G` | injectK | | `InjectK[F[_], G[_]]` | `InjectK` alias |
| `⊥` | bottom | | N/A | `Nothing` |
| `⊤` | top | | N/A | `Any` |

## <a id="contributing" href="#contributing"></a>How can I help?

The cats community welcomes and encourages contributions, even if you are completely new to cats and functional programming. Here are a few ways to help out:
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31 changes: 0 additions & 31 deletions docs/src/main/tut/typeclasses/symbols.md
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