Bend/docs/imports.md

Import System

Case Sensitivity

All import paths are case-sensitive. Ensure that the case used in import statements matches exactly with the file and directory names.

Syntax

Imports can be declared two ways:

from path import name
# or
import path/name

Project Structure

Let's assume we have a bend project with the following structure:

my_project/
├── main.bend
├── utils/
│   ├── helper.bend
│   │   └── def calc
│   └── math.bend
│       ├── def add
│       └── def subtract

Importing Relative Paths

Paths starting with ./ or ../ are imported relative to the file.

Example:

# if used inside `my_project/*.bend`
from ./utils import helper
# if used inside `my_project/*/*.bend`
import ../utils/helper

This will bind calc from helper.bend as helper/calc.

Importing Absolute Paths

Otherwise, paths imported are relative to the folder of the main file.

Example:

from utils import math
# or
import utils/math

This will bind add and subtract from math.bend as math/add and math/subtract.

Importing Specific Top-Level Names

You can import specific top-level names from a file.

Example:

from utils/helper import calc
from utils/math import (add, subtract)
# or
import (utils/helper/calc, utils/math/add, utils/math/subtract)
# or
import utils/helper/calc
import utils/math/add
import utils/math/subtract

This will bind the names calc, add and subtract from their respective files.

Importing All Names

You can import all top-level names from a file using the wildcard *.

Example:

from utils/math import *

This will bind the names add and subtract from math.bend.

Importing All .bend Files from a Folder

You can import all .bend files from a folder using the wildcard *.

Example:

from utils import *

This will bind the names from helper.bend and math.bend, as helper/calc, math/add and math/subtract.

Aliasing Imports

You can alias imports to a different name for convenience.

Importing a File with Alias

Import the file top-level name from file.bend aliased to alias, and all other names as alias/name.

Example:

from utils import helper as utilsHelper
import utils/math as mathLib

This will bind the names from helper.bend and math.bend, as utilsHelper/calc, mathLib/add and mathLib/subtract.

Importing Specific Names with Aliases

You can import specific top-level names and alias them to different names.

Example:

from utils/helper import calc as calcFunc
from utils/math import (add as addFunc, subtract as subFunc)
# or
import (utils/math/add as addFunc, utils/math/subtract as subFunc)

This will bind calc, add and subtract as calcFunc, addFunc and subFunc from their respective files.

Project Structure

Let's assume we have a bend project with the following structure:

my_project/
├── main.bend
├── types/
│   ├── List.bend
│   │   └── type List: Nil | (Cons ..)
│   └── List/
│       ├── concat.bend
│       │   └── def concat
│       └── append.bend
│           └── def append
│           └── def helper

Importing data types

You can import a data type and its constructors by only importing its name.

Example:

from types/List import List
# behaves the same as 
from types/List import (List, List/Nil, List/Cons)

Importing only List from List.bend will import the type List and bind its constructors name List/Nil and List/Cons.

Importing files with a top level name equal to its name

When a file and a top-level name in it share a name, for example, List.bend, concat.bend and append.bend, the bind of that import is simplified to the file name.

Example:

from types/List import append

This will bind append and append/helper from append.bend.

Files and directories with the same name

When files and directories share a name, both share the import namespace:

from types/List import (List, concat)

This will attempt to import from both the List.bend file and the List folder, resulting in the binds List/Nil, List/Cons and concat.

from types/List import *

This will import all the names from List.bend, then all the files inside the List folder, resulting in the binds List/Nil, List/Cons, concat, append and append/helper.

In both cases, if a name is present as a top-level name on the file, and as a .bend file name inside the folder, it will result in an error.

If you only want to import List.bend and not search the files in its folder, you can use the import path syntax:

import types/List