tosuto

a simple scripting language

Tosuto is designed to be easy to write and extend, as well as easily interact with C++.

In the future, I want this language to have something special about it, so I'll add some i18n capabilities to it.

An example

@entrypoint
main : argv {
  bread := "bread"

  toaster.(bread)
  log.(bread) // output: toast
}

toaster := [|
  bread = "toast"
  `()` : my* bread* -> bread = my.bread
|]

Here's an example program that toasts some bread.

We create a main function, marked with the @entrypoint attribute. Inside the function, we define a variable bread whose value is "bread", and we pass it to the overloaded call operator on an object called toaster, which takes two arguments: an implicitly passed my, as well as bread. Both are passed by reference, so when we set the argument bread to my.bread, the outer variable bread is set to "toast".

Syntax

Identifiers

Each source file is lexed in UTF-32, allowing special characters to be used in identifiers and strings. Currently, alphanumeric characters, $, _, the top half of extended ASCII, and half-width katakana characters are supported, due to me being too lazy to manually add any more character ranges.

Keywords

name	action
next	in for loops, this acts like the continue keyword in other languages.
break	this breaks out of a loop early.
ret	this is like the return keyword in other languages. it stops execution of a function early, and optionally returns a value.
false	represents the constant false.
true	represents the constant true.
nil	represents the constant nil.
if	starts the declaration of an if statement.
elif	equivalent to what occurs when else if is typed in other languages.
else	defines the else case of an if statement that gets executed when none of the other branches' conditions evaluate to true.
for	declares a for loop.

Expressions

infix operator	action
a := b	declares a variable a with value b.
a (+|-|*|/|%)= b	sets a to a (+|-|*|/|%) b
a (+|-|*|/|%) b	evaluate a (+|-|*|/|%) b

unary operator	action
+a	if a is a number, return a, else throw
-a	if a is a number, return -a, else throw
a*	dereference a, only useful with objects that have member *deref
!a	if a is truthy, return false, else return true