---
title: "KCL Modules"
excerpt: "Documentation of modules for the KCL language for the Zoo Modeling App."
layout: manual
---

`KCL` allows splitting code up into multiple files.  Each file is somewhat
isolated from other files as a separate module.

When you define a function, you can use `export` before it to make it available
to other modules.

```
// util.kcl
export fn increment(x) {
  return x + 1
}
```

Other files in the project can now import functions that have been exported.
This makes them available to use in another file.

```
// main.kcl
import increment from "util.kcl"

answer = increment(41)
```

Imported files _must_ be in the same project so that units are uniform across
modules. This means that it must be in the same directory.

Import statements must be at the top-level of a file. It is not allowed to have
an `import` statement inside a function or in the body of an if-else.

Multiple functions can be exported in a file.

```
// util.kcl
export fn increment(x) {
  return x + 1
}

export fn decrement(x) {
  return x - 1
}
```

When importing, you can import multiple functions at once.

```
import increment, decrement from "util.kcl"
```

Imported symbols can be renamed for convenience or to avoid name collisions.

```
import increment as inc, decrement as dec from "util.kcl"
```