// the basics of cosy

// print to output
print 'hello world!'


// variables and types
let a = true     // Boolean
let b = 1.2      // Number
let c = 'hello'  // String
let d = [3, 4]   // Array

struct Point {   // Struct
    let x
    let y
    let text = 'default value'
}
// instantiate struct
let point = Point { x = 3, y = 5 }
print point

// variables are immutable by default
let immutable = 42
// immutable = 24 // error

// use the `mut` keyword to create a mutable variable
mut mutable = 42
mutable = 24 // ok


// conditional branching
if 3 < 5 and 4 == 4 {
    print 'true'
} else {
    print 'false'
}


// loop with counter
for i in 0..3 {
    print 'loop #' + i
}

// loop without counter
for 0..3 {
    print 'no counter'
}

// loop with condition
mut j = 0
for j < 3 {
    print 'conditional loop #i'
    j = j + 1
}

// loop over array
for i in [5, 6, 7] {
    print 'array value: ' + i
}


// functions
fn say(name) {
    print 'hello ' + name
}
say('world')

// lambda functions
let square = fn(value Num) {
    return value * value
}
print '5 * 5 = ' + square(5)

// functions can return functions
fn say_with_extra_text(extra_text Str) {
    return fn(text) {
        print text + extra_text
    }
}
let print_courteously = say_with_extra_text(', please!')
print_courteously('make me a sandwich')

// functions can tage functions as arguments
fn do_n_times(f Fn(Num), n Num) {
    for i in 0..n {
        f(i)
    }
}
do_n_times(fn(x Num) { print 'i\'m called ' + (x + 1) + ' time(s)' }, 3)

// functions act as closures
fn counter(start, increment) Fn() Num {
    mut count = start
    return fn() {
        count = count + increment
        return count
    }
}
print 'counting down...'
let count_down = counter(3, -1)
print count_down()
print count_down()
print count_down()


// dead code is not allowed
fn dead_code() {
    print 'i\'m always printing this'
    return true
    // print 'i\'m never printing this' // error
}
dead_code()


// shadowing of variables are not allowed
{
    let unique = true
    {
        //let unique = 3 // error
    }
    print unique
}


// unused variables are not allowed
let unused = 42 // error if the line below is removed
print unused
// because of this, we also have to use the variables defined at the top
if !a print b + c + d + immutable + mutable

// variables can be marked purposely unused with an underscore
fn some_function(_unused) {
    print 'the arg is unused, but that\'s okay'
}
some_function(1234)


// that's it for the basics
// for more examples see:
// https://github.com/anissen/cosy/tree/master/test/scripts

MIT License

Copyright (c) 2021 Anders Nissen

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.