Simple language built to experiment with writing a custom parser. Not even close to being complete or even usable yet.

Syntax is a mashup of some languages I enjoy, and is designed to be relatively simple to parse and work with. That said, it will probably be revolting to actually program with.

The main idea Arroyo is built around is that everything is an expression, there is no concept of statements. The problem with this is that something like my_function(args) cannot be parsed as a function call as it is in other languages without introducing some ambiguity (i.e. is it a function call, or is it the expression my_function followed by the block (args)?).

To get around this, Arroyo uses the horrible notation of callable->(arguments), which, while dreadful, is unambiguous.

Some other things to note:

• , is whitespace. It doesn't change meanings or precedence anywhere.
• everything is an expression. You can use any code in an assignment statement for example.
• The parser hates you and is not afraid to let you know.
• print, eval, and require are implemented as unary operators, and as such, do not follow the standard function->(args) notation. This will hopefully change later on.
• Variable scope is very naively implemented, be careful not to overwrite values in functions.

In summary, if you're seriously considering using Arroyo, I advise that you go outside, take some deep breaths, and think about all the wonderful languages that you can use instead.

Here are some simple examples of what Arroyo actually looks like:

-- map array's values to a function
fn map(a:array, f:function) (
    ret <- []
    for x in a (
        ret << f->(x)
    )
)

map->([1,2,3], fn(_)_+1)  -- => [2,3,4]

-- simple, inaccurate definite integral
fn integral(f:function, low:real, high:real) (
  sum <- 0.0
  loop i <- low, while i < high
    sum <- 0.01 * (func->(i <- i + 0.01)) + sum
)

integral->(fn(x) x*x, 1, 10) -- => ~334

Copyright (C) 2012 Erik Price

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