Skip to main content

imitation of let expression like a Haskell.

Project description

[![Build Status](https://travis-ci.org/hachibeeDI/letexpr.png?branch=master)](https://travis-ci.org/hachibeeDI/letexpr)

# letexpr

That is python module imitate `let expression` like a Haskell.

And support lazy evaluation.


# Installation

```bash
$ pip install https://github.com/hachibeeDI/letexpr/archive/master.zip
```


# Example

```python
from letexpr import let, expr

# expr(x) = lambda x: lambda: x

answer = (
let()
| ('x', expr(10))
| ('y', expr(20))
| ('size', lambda x, y: x * y)
| ('hoge', lambda x, y: 'fooo')
).in_(lambda x, y, size:
'x = {x}, y = {y}, x * y = {size}'.format(x=x, y=y, size=size))
print answer
# => 'x = 10, y = 20, x * y = 200'


# with List Comprehensions
even_or_odd = [
(let()
| ('_i', expr(str(i)))
| ('r', expr('even' if i % 2 == 0 else 'odd'))
).in_(lambda _i, r:
_i + ' is an ' + r + ' number.')
for i in range(1, 5)]
print even_or_odd
# => ['1 is odd number.', '2 is even number.', '3 is odd number.', '4 is even number.']


# with anonymous function
let_ = (let()
| ('x', expr('x'))
| ('y', expr('y'))
)
@let_.in_()
def _(x, y):
return x + y
print let_.end
# => 'xy'

```

# Testing


```bash
$ pip install nose
$ nosetests --with-doctest
```

Project details


Release history Release notifications

This version
History Node

0.3.5

History Node

0.3.1

History Node

0.1

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Filename, size & hash SHA256 hash help File type Python version Upload date
letexpr-0.3.5.tar.gz (3.3 kB) Copy SHA256 hash SHA256 Source None Jul 14, 2014

Supported by

Elastic Elastic Search Pingdom Pingdom Monitoring Google Google BigQuery Sentry Sentry Error logging CloudAMQP CloudAMQP RabbitMQ AWS AWS Cloud computing Fastly Fastly CDN DigiCert DigiCert EV certificate StatusPage StatusPage Status page