gofu
a scripting language toolkit in Go
intro
gofu aims to provide a flexible toolkit for creating custom scripting languages in Go.
functions
Functions have a name, an argument list, a result list and a body.
p := gofu.Pos("Test", -1, -1)
add := gofu.Func("+", []gofu.Type{types.Int(), types.Int()}, []gofu.Type{types.Int()},
func(pos gofu.TPos, thread *gofu.TThread, _func *gofu.TFunc, pc *int) error {
stack := thread.Stack()
stack.Push(types.Int(), stack.Pop().Value().(int) + stack.Pop().Value().(int))
return nil
})
scope := gofu.Scope()
scope.BindSlot("+", types.Func(), add)
block := gofu.Block()
c := forms.Call(p, forms.Id(p, "+"), forms.Literal(p, types.Int(), 35), forms.Literal(p, types.Int(), 7))
c.Compile(scope, block)
block.Emit(ops.Stop())
thread := gofu.Thread(scope)
block.Run(thread, 0)
The same thing could be accomplished by manually emitting operations.
block.Emit(ops.Push(types.Int(), 35))
block.Emit(ops.Push(types.Int(), 7))
block.Emit(ops.Call(p, add))
block.Emit(ops.Stop())
fimps.Compile may be used to compile function bodies.
fimp, err := fimps.Compile(forms.Literal(p, []gofu.Type{types.Int()}, 42), block)
fortyTwo := gofu.Func("fortyTwo", nil, []gofu.Type{types.Int()}, fimp)
scope.BindSlot("fortyTwo", types.Func(), f)
multiple dispatch
The following example will dispatch to the right function based on the argument and push "Bool!" on the stack.
f1 := gofu.Func("foo", []gofu.Type{types.Bool()}, []gofu.Type{types.Int()},
func(pos gofu.TPos, thread *gofu.TThread, _func *gofu.TFunc, pc *int) error {
stack := thread.Stack()
stack.Pop()
stack.Push(types.String(), "Bool!")
return nil
})
f2 := gofu.Func("foo", []gofu.Type{types.Int()}, []gofu.Type{types.Int()},
func(pos gofu.TPos, thread *gofu.TThread, _func *gofu.TFunc, pc *int) error {
stack := thread.Stack()
stack.Pop()
stack.Push(types.String(), "Int!")
return nil
})
m := gofu.Multi("foo", 1, f1, f2)
block.Emit(ops.Push(types.Bool(), true))
block.Emit(ops.Call(p, m))
block.Emit(ops.Stop())
macros
Macros are called at compile time and may emit different code depending on arguments.
scope.BindSlot("reset",
types.Macro(),
gofu.Macro("reset", 0,
func(pos gofu.TPos, args []gofu.Form, scope *gofu.TScope, block *gofu.TBlock) error {
block.Emit(ops.Reset())
return nil
}))
types
The following list of types are provided but optional, anything implementing gofu.Type may be used as a type.
- Any: Any - Anything
- Bool: Any - t/f
- Char: Any - Characters
- Func: Any Target - Functions
- Int: Any Num - Integers
- Maybe[T]: Any - Contains T or Nil
- Meta: Any - The type of types
- Multi: Any Target - Multimethods
- Nil - Nothing, it's only value being
_ - Num: Any - Parent of all numbers
- Seq[T]: Any - Parent of all sequences
- Stack[T]: Any Seq[T] - Stacks of values
- String: Any Seq[Char] - Strings
- Target: Any - Callable values
repl
A primitive REPL is provided, it reads one form at a time and prints the stack after each evaluation.
$ cd bin
$ ./mk
$ ./repl
gofu v1
+(35 7)
[42]
Parens may be used to group forms.
(1 2 3)
[1 2 3]
The stack may be directly modified using d and reset.
(1 2 3)
[1 2 3]
d
[1 2]
reset
[]
Code may be executed conditionally using if.
if(t 1 2)
[1]
if(f 3 4)
[1 4]
Functions may be called by suffixing names with argument lists.
+(35 7)
[42]
New functions may be defined using func.
func(foo () (Int) 42)
[]
foo
[42]
Values may be bound to identifiers using bind.
bind(foo 42)
[]
foo
[42]
The REPL is heavily parameterized and assumes very little about the actual language.
scope := gofu.Scope()
block := gofu.Block()
thread := gofu.Thread(scope)
utils.Repl(scope, parsers.Any(), block, thread)
