[RFC] Error Handling

[mertyildiran]

Implement error handling using the decision block and catch statement. This feature will also require implementing a core library named errors to fetch the error code. The syntax will look like this:

from errors import index_out_of_range

num def return_zero()
    num r = 0
    retun r
end

num def return_first(num list a)
    num r = a[0]
    retun r
end {
    catch index_out_of_range() : return_zero()
}

num def get_index_of_using_sum(num list a, num x, num y)
    num z = x + y
    num r = a[z]
    return r
end {
    catch index_out_of_range() : return_first(a)
}

print get_index_of_using_sum([1, 2, 3, 4, 5], 1, 4) # Should print 1

print get_index_of_using_sum([], 1, 1) # Should print 0

In that way, one can implement his/her own function to return the desired error code instead of using the errors library:

num def index_out_of_range()
    num r = 8
    return r
end

num def return_zero()
    num r = 0
    retun r
end

num def return_first(num list a)
    num r = a[0]
    retun r
end {
    catch index_out_of_range() : return_zero()
}

num def get_index_of_using_sum(num list a, num x, num y)
    num z = x + y
    num r = a[z]
    return r
end {
    catch index_out_of_range() : return_first(a)
}

print get_index_of_using_sum([1, 2, 3, 4, 5], 1, 4) # Should print 1

print get_index_of_using_sum([], 1, 1) # Should print 0