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# clean-compiler
The [Clean][clean] compiler.
The official Clean compiler can be found at
[https://svn.cs.ru.nl/repos/clean-compiler/][cocl].
This is a fork to implement experimental new features.
---
## Contents
1\. [Syntactic sugar](#1-syntactic-sugar)
1.1. [Lambda-case](#11-lambda-case)
1.2. [Tuple constructors](#12-tuple-constructors)
2\. [Syntax changes](#2-syntax-changes)
2.1. [Use of module header keywords](#21-use-of-module-header-keywords)
---
## 1. Syntactic sugar
### 1.1. Lambda-case
Similar to [GHC's LambdaCase][ghclambdacase], this is a sugar for lambda
expressions where the argument is only used in a `case .. of` expression. For
example,
```clean
\case of
0 = "zero"
1 = "one"
_ = "many"
```
is transformed to
```clean
\x -> case x of
0 = "zero"
1 = "one"
_ = "many"
```
where `x` is a fresh variable.
The extension to the grammar:
```
LambdaAbstr = ...
| \case of {CaseAltDef}+
```
### 1.2. Tuple constructors
There are now tuple constructors that can be used curriedly, similar to GHC and
the way the tuple type could be curried already. For example:
```clean
import StdFunc
Start = flip (,) 5 10
```
## 2. Syntax changes
### 2.1. Use of module header keywords
Four keywords are now only recognised on the topmost level. This allows for
using them as a record field, for example:
```clean
:: MyType = { module :: Int }
```
The keywords are:
- `module`
- `definition`
- `implementation`
- `system`
It is not allowed to define a function named as one of these keywords.
[clean]: http://clean.cs.ru.nl
[cocl]: https://svn.cs.ru.nl/repos/clean-compiler/
[ghclambdacase]: https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#lambda-case
|
