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Customization.md

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Customization

lambdex supports user customization for both the compiler and the formatter. To customize, one should provide a config file named .lambdex.cfg in the file system. The file is written in INI format. Once configured, the settings will never be changed at runtime.

If you want to completely disable customization, simply set environment variable LXNOCFG=1.

List of environment variables that affect the behavior of lambdex:

  • LXNOCFG=1 disables any customization;
  • LXALIAS=1 enableds keyword and operator aliasing.

Config File Resolving

lambdex will search for the config file in the directories specified below:

  1. All parents of the input file, if lambdex is run as formatter and not reading from stdin;
  2. All parents of the importer module, if lambdex is imported by a user script / module;
  3. CWD and all its parents.

The first one matched will be adopted. Below are several examples for better understanding.

Example 1

Suppose lambdex is run as formatter (such as lxfmt), and two input files /path1/to/file1.py, /path2/to/file2.py supplied, and CWD is /path3/cwd/. The config file will be searched from (note that the two inputs may not share a config file):

# Search paths for input 1
/path1/to/
/path1/
/
/path3/cwd/
/path3/
/

# Search paths for input 2
/path2/to/
/path2/
/
/path3/cwd/
/path3/
/

Example 2

Suppose lambdex is imported by /path/to/file.py, and CWD is /path3/cwd/. The config file will be searched from:

/path/to/
/path/
/
/path3/cwd/
/path3/
/

Example 3

Suppose lambdex is imported in an REPL, and CWD is /path3/cwd/. The config file will be searched from:

/path3/cwd/
/path3/
/

Keyword and Operator Aliasing

Aliasing allows you to use keywords and operetors other than the default ones. By default, aliasing is disabled. One should set environment variable LXALIAS=1 to enable it.

Aliasing should be specified in the [aliases] section in .lambdex.cfg, e.g.

# .lambdex.cfg
[aliases]
def_ = Def
if_ = If
else_ = Else
return_ = Return
Assignment = <=

The configuration above allows you to write code like

from lambdex import Def  # <-- Note here

max_plus_one = Def(lambda a, b: [
    If[a > b] [
        larger <= a,
    ].Else [
        larger <= b,
    ],
    Return[larger + 1]
])

Full list of alias entries goes here

# .lambdex.cfg
[aliases]
# Keywords
def_        = def_
if_         = if_
elif_       = elif_
else_       = else_
for_        = for_
while_      = while_
with_       = with_
try_        = try_
except_     = except_
finally_    = finally_
yield_      = yield_
yield_from_ = yield_from_
pass_       = pass_
return_     = return_
from_       = from_
raise_      = raise_
global_     = global_
nonlocal_   = nonlocal_
del_        = del_
break_      = break_
continue_   = continue_
callee_     = callee_
async_def_  = async_def_
async_with_ = async_with_
async_for_  = async_for_
await_      = await_

# Operators
# From now on, the fields should start with captialized letters
Assignment   = <
As           = >

Language Extension

Extensions should be specified in the [features] section in .lambdex.cfg. To turn on a specific feature, simply set the entry to ON.

Full list of extensions goes here:

[features]
await_attribute = OFF
implicit_return = OFF