# Pattern Matching

## Syntax

```fsharp
match <expr> {
    case <case expr>: {
        <code block>
    }
}
```

`<case expr>` refers to any of the following:

* An enum literal (e.g. `Circle()` in the below example)
  * Currently, you cannot pattern match on any field that is another enum literal. Support is currently being implemented for this.&#x20;
* A string (e.g. `"hello"`)
* An int (e.g. `30`)
* A decimal (e.g. `5.0`)
* A boolean (e.g. `true`)
* A char (e.g. `'a'`)
* \[Support Coming Soon] ~~Wildcard~~
* \[Support Coming Soon] ~~Array literal (e.g. `[2]string{"hello", "world"}`)~~
* \[Support Coming Soon] ~~Slice literal (e.g. `[]string{"hello", "world"}`)~~

## Working Example

{% tabs %}
{% tab title="Gauntlet" %}

```fsharp
package main

import "fmt" as fmt
import "strconv" as strconv

enum Shapes {
    Circle(diameter: Int, color: String)
    Square(width: Int, height: Int, color: String)
    Triangle(base: Int, width: Int, height: Int, color: String)
}

fun main(): Unit {
    fmt.println("I only like red triangles. Let's see...")
    
    let myShape = Triangle(base: 10, width : 5, height : 20, color : "red")
    
    match myShape {
        case Triangle(base: let b, height: let height, color : "red") : {
            fmt.println("It's a red triangle with a height of " + strconv.itoa(height) + " and base length of " + strconv.itoa(b) + "!")
        }
        case Square(width : let width, color : "red") : {
            fmt.println("It's a red square with a width of " + strconv.itoa(width))
        }
        case Circle(diameter: let diameter, color : "red") : {
            fmt.println("It's a red circle with a diameter of " + strconv.itoa(diameter))
        }
    }
}
```

{% endtab %}

{% tab title="Transpiled" %}

```go
package main

import fmt "fmt"
import strconv "strconv"

type Case343818345 struct {
diameter int
color    string
}

type Case421059818 struct {
width  int
height int
color  string
}

type Case499594069 struct {
base   int
width  int
height int
color  string
}

func main() {
fmt.Println("I only like red triangles. Let's see...")
myShape := map[int]any{499594069: Case499594069{base: 10, width: 5, height: 20, color: "red"}}
if _, exists := myShape[499594069]; exists {

	if height, b := myShape[499594069].(Case499594069).height, myShape[499594069].(Case499594069).base; (func() bool {
		return (myShape[499594069].(Case499594069).base == (b)) && (myShape[499594069].(Case499594069).height == (height)) && (myShape[499594069].(Case499594069).color == ("red"))
	})() {
		fmt.Println("It's a red triangle with a height of " + strconv.Itoa(height) + " and base length of " + strconv.Itoa(b) + "!")
	}
}
if _, exists := myShape[421059818]; exists {

	if width := myShape[421059818].(Case421059818).width; (func() bool {
		return (myShape[421059818].(Case421059818).width == (width)) && (myShape[421059818].(Case421059818).color == ("red"))
	})() {
		fmt.Println("It's a red square with a width of " + strconv.Itoa(width))
	}
}
if _, exists := myShape[343818345]; exists {

	if diameter := myShape[343818345].(Case343818345).diameter; (func() bool {
		return (myShape[343818345].(Case343818345).diameter == (diameter)) && (myShape[343818345].(Case343818345).color == ("red"))
	})() {
		fmt.Println("It's a red circle with a diameter of " + strconv.Itoa(diameter))
	}
}
// Eliminates any 'unused variable' errors
_ = myShape

}

```

{% endtab %}

{% tab title="Output" %}

```
I only like red triangles. Let's see...
It's a red triangle with a height of 20 and base length of 10!
```

{% endtab %}
{% endtabs %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://gauntletlang.gitbook.io/docs/advanced-features/pattern-matching.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.