hs2lazy -- Haskell to Lazy K compiler

What is this?

This is a translator from a subset of Haskell to Lazy K.

How to compile

You can build hs2lazy with GHC by following command:

ghc -o hs2lazy --make Main.hs

How to use

hs2lazy [source files]

If multiple source files are given, they are concatenated in the order specified. Output Lazy K code is written to standard output. Prelude module is not automatically loaded. So, you may specify examples/hs2lazy-prelude.hs first, like following:

hs2lazy examples/hs2lazy-prelude.hs foo.hs >foo.lazy

How to write source code

In Lazy K, input and output streams are represented as infinite lists of numbers (256 represents EOF). Hs2lazy programs handle I/O in similar way.

In Haskell, type of main function is IO (). But in hs2lazy, that is:

main :: Stream -> Stream

The Stream type is defined in hs2lazy-prelude.hs as

data Stream = Stream Char Stream

The input is a infinite stream of characters. For example:

Stream 'f' $ Stream 'o' $ Stream 'o' $ Stream eof $ Stream eof ...

eof is defined as (chr 256).

Streams can be converted to/from strings by fromStream and toStream defined in hs2lazy-prelude.hs. For example, following program reverses the input character-by-character.

main = toStream . reverse . fromStream

Or simply,

main = interact reverse

interact converts a String-to-String function to a Stream-to-Stream function.

License

Type.hs is based on Typing Haskell in Haskell. See Lisence.thih for the license of it.