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Clojure-like utilities

Project description

# clj

`clj` is a Python module for those times when you did too much Clojure and
came back to Python thinking where are all these `distinct`, `drop-while`,
`cycle`, `first`, etc.

## Install

pip install clj

## Usage

Functions on sequences are in `clj.seqs`; functions that operate on functions
are in `clj.fns`.

### Example

```clojure
;; Clojure
(println (count (distinct (filter even? (map inc coll)))))
```

```python
# Python
from clj.seqs import count, distinct
from clj.fns import inc

even = lambda e: ~e&1

print(count(distinct(filter(even, map(inc, coll)))))
```

Note that `count()` works on both sequences in generators; in the latter case
it doesn’t load everything in memory like e.g. `len(list(g))` would do.

## Core Ideas

* Lazy by default. All functions should work on arbitrary iterators and
return generators.
* This is Python. We keep Python’s semantics instead of trying to reproduce
Clojure in Python (e.g. `0` and `[]` are logically true in Clojure but false
in Python; `None` is not equivalent to an empty collection).
* Don’t Reinvent the Wheel. Python already provides things like `map` and
`filter`. We don’t reimplement them unless they miss something (e.g. Python’s
`range` can’t be called without argument to yield an infinite sequence).

## Support

### Sequences (`clj.seqs`)

`clj.seqs` aims to implement all Clojure functions that operate on sequences
(see [the list here][seqs]).
They all work on iterables and return generators by default (Python’s closest
equivalent of lazy seqs). We don’t support transducers.

[seqs]: http://clojure.org/reference/sequences

| Clojure | `clj.seqs` | Comment |
|-------------------|:----------------|----------------------------------|
| `distinct` | `distinct` | |
| `filter` | - | Use Python’s built-in `filter`. |
| `remove` | `remove` | |
| `for` | - | Use `for … in`. |
| `keep` | `keep` | |
| `keep-indexed` | `keep_indexed`  | |
| `cons` | `cons` | |
| `concat` | `concat` | |
| `lazy-cat` | - | Use `concat`. |
| `mapcat` | `mapcat` | |
| `cycle` | `cycle` | |
| `interleave` | `interleave` | |
| `interpose` | `interpose` | |
| `rest` | `rest` | |
| `next` | - | Use `rest`. |
| `fnext` | - | Use `second`. |
| `nnext` | - | Use `rest(rest(…))` |
| `drop` | `drop` | |
| `drop-while` | `drop_while` | |
| `nthnext` | - | |
| `take` | `take` | |
| `take-nth` | `take_nth` | |
| `take-while` | `take_while` | |
| `butlast` | `butlast` | |
| `drop-last` | `drop_last` | |
| `flatten` | `flatten` | |
| `reverse` | - | Use Python’s `reversed`. |
| `sort` | - | Use Python’s built-in `sort`. |
| `sort-by` | - | Use `sort(…, key=your_function)`.|
| `shuffle` | `shuffle` | |
| `split-at` | `split_at` | |
| `split-with` | `split_with` | |
| `partition` |   | |
| `partition-all` |   | |
| `partition-by` |   | |
| `map` | - | Use Python’s built-in `map`. |
| `pmap` | - | |
| `replace` | `replace` | |
| `reductions` | `reductions` | `(reductions f i c)` becomes `reductions(f, c, i)` |
| `map-indexed` | `map_indexed` | |
| `seque` | - | |
| `first` | `first`  | |
| `ffirst` | `ffirst` | |
| `nfirst` | `nfirst` | |
| `second` | `second` | |
| `nth` | `nth` | |
| `when-first` | - | (macro) |
| `last` | `last` | |
| `rand-nth` | - | Use Python’s `random.choice`. |
| `zipmap` | `zipmap` | |
| `into` | - | |
| `reduce` | - | Use Python’s built-in `reduce`. |
| `set` | - | Use Python’s `set`. |
| `vec` | - | Use Python’s `list`. |
| `into-array` | - | Use Python’s `list`. |
| `to-array-2d` | - | |
| `frequencies` | - | Use Python’s `collections.Counter`.|
| `group-by` | `group_by` | |
| `apply` | - | Use the `f(*args)` construct. |
| `not-empty` | - | |
| `some` | `some` | |
| `seq?` | `is_seq` | |
| `every?` | `every` | |
| `not-every?` | `not_every` | |
| `not-any?` | `not_any` | |
| `empty?` | - | |
| `doseq` | - | Use `for … in` |
| `dorun` | `dorun` | |
| `doall` | - | Use Python’s `list`. |
| `realized?` | - | |
| `seq` | - | |
| `vals` | - | Use Python’s `dict.values`. |
| `keys` | - | Use Python’s `dict.keys`. |
| `rseq` | - | |
| `subseq` |   | |
| `rsubseq` |   | |
| `lazy-seq` | - | (macro) |
| `repeatedly` | `repeatedly` | |
| `iterate` | `iterate` | |
| `repeat` | `repeat` | `(repeat n x)` becomes `repeat(x, n)`.|
| `range` | `range` | Prefer Python’s `range` for everything but infinite generators.|
| `line-seq` | - | Loop over an `io.BufferedReader`.|
| `resultset-seq` | - | |
| `re-seq` | - | Use Python’s `re.finditer`. |
| `tree-seq` | - | |
| `file-seq` | - | |
| `xml-seq` | - | |
| `iterator-seq` | - | |
| `enumeration-seq` | - | |

We also implemented `count`, which uses Python’s `len` when possible and
fallbacks on a `for` loop for other cases.

### Functions (`clj.fns`)

`clj.fns` defines miscellaneous functions as well as functions that work on
functions.

| Clojure | `clj.fns` | Comment |
|-------------------|:----------------|----------------------------------|
| `identity` | `identity` | |
| `partial` | - | Use Python’s `functools.partial` |
| `comp` | `comp` | |
| `complement` | `complement` | |
| `constantly` | `constantly` | |
| `juxt` | `juxt` | |

| Clojure | `clj.fns` | Comment |
|-------------------|:----------------|----------------------------------|
| `inc` | `inc` | |
| `dec` | `dec` | |

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