Ergolas (WIP)

This is just an embeddable random golang language for scripting. Recently I use Golang very often and sometimes I want to add some extensibility features to my projects using some kind of scripting languages or DSL so I made this mini language for experimenting. There is an included tree walking interpreter but I plan to make it really easy to just parse an expression and get an AST to evaluate with a custom interpreter.

The syntax is very simple and pretty general and inherits many things from Lisp, REBOL/Red and Julia.

println "Hello, World!"

Features

• Parser
  • Function calls without parentheses
  • Property access
  • Quoted forms
  • Binary operators
  • Quasi-quotes with : for quoting and $ for unquoting (might change : to # and comments to //)
  • Unary operators
  • String templating (for now missing, maybe something can be done just using quasiquotes)
• Interpreter
  • Simple tree walking interpreter
    • Basic operators and arithmetic
    • Basic printing and exiting
    • Basic variable assignment
    • Lexical scoping
    • Control flow
    • Objects and complex values
    • Dynamic scoping
    • Hygienic macros
  • More advanced interpreters...
• Easily usable as a library
• Small standard library
• Interop from and with Go
• Tooling
  • Syntax highlighting for common editors
  • PKGBUILD for easy global installation on Arch Linux thorough GitHub releases (mostly for trying this out with GitHub Actions)

Usage

To try this out in a REPL (with colors!)

$ go run ./cmd/repl

Reference

Literals

# Integer
1

# Decimal
3.14

# Identifier
an-Example_identifier

# String
"an example string"

# List (?) (not implemented)
[1 2 3 4 5] # equivalent to "List 1 2 3 4 5"

# Maps (?) (not implemented)
{ a -> 1, b -> 2, c -> 3 }

Comments

# This is an inline comment

Functions

Function call don't require parentheses if they

# [x] Parses ok, [x] Evals ok
println "a" "b" c" 

# [x] Parses ok, [x] Evals ok
exit 1

Anonymous Functions

# [x] Parses ok, [ ] Evals ok

# anonymous function with params
my-func := fn x y { x + y }

# [ ] Parses ok, [ ] Evals ok

# anonymous lexical block without params, can be called with a context
my-block := { x + y }
ctx := Map [ x -> 1, y -> 2 ]
call my-block ctx

Operators

The following binds "a" to 9, arithmetic operators don't have any precedence and are all left associative. There are a only a few right associative operators that for now just are :=, :: even if only := is used for binding variables, :: will later be used to tell the type of variables.

# [x] Parses ok, [x] Evals ok
a := 1 + 2 * 3

Overloading

# [x] Parses ok, [ ] Evals ok
operator lhs ++ rhs {
    return List.join lhs rhs
}

Quotes

# [x] Parses ok, [ ] Evals ok
a := (1 + 1) # 2
b := :(1 + 1) # :(1 + 1)

Misc

Some more examples and ideas for the language syntax and semantics

# [x] Parses ok, [ ] Evals ok
len := (v.x ^ 2) + (v.y ^ 2)

# [x] Parses ok, [ ] Evals ok
if { a > b } {
    println "True case"
} {
    println "False case" 
}

# [x] Parses ok, [ ] Evals ok
my-list-1 := list 1 2 3 4 5

# [x] Parses ok, [ ] Evals ok
for item my-list-1 {
    printfln "item = {}" item
}