Snabl

Snabl is a simple Go scripting language.

Setup

git clone https://github.com/codr7/snabl.git
cd snabl
go build main/snabl.go

./snabl
  say "hello"

hello

./snabl help
Snabl v4

Usage:
snabl [command] [file1.sl] [file2.sl]...

Commands:
eval	Evaluate code and exit
read	Dump forms and exit
emit	Dump code and exit
repl	Evaluate code and start REPL

Syntax

Snabl uses strict prefix syntax with optional parens; as a consequence, functions and macros have fixed arity.

Types

Bool

The type of boolean values.

  = T F

F

Form

The type of source code forms.

Fun

The type of functions.

  defun foo(x) x
  foo 42

42

Int

The type of integer values.

Macro

The type of macros.

Pos

The type of source code positions.

  1 2 3 pos
  
repl@1:7

Prim

The type of primitives, functions implemented in Go.

Slice

The type of slices.

  len [1 2 3]

3

String

The type of string values.

  len "foo"

3

Time

The type of time intervals.

  mins 10
  
10m0s

Environments

Curlies may be used to create new compile time environments.

  {def foo 42 foo}

[42]
  foo

repl@1:1 Error: foo?

Debugging

debug may be used to toggle generation of debug info and panic on errors.

  fail "failing"
  
Error: failing
  debug
  
  fail "failing"
  
panic: repl@1:6 Error: failing

trace may be used to toggle tracing of operations and stack contents.

  trace
  
1 STOP []
  1 2 3
  
3 PUSH_INT 1 []
5 PUSH_INT 2 [1]
7 PUSH_INT 3 [1 2]
9 STOP [1 2 3]
3

Testing

test expected expr evaluates expr and compares the result with expected.

  test T = 1 1
  
T = 1 1
  test T = 1 2
  
T = 1 2
TEST FAILED repl@1:8 F

You may find more examples here.

Benchmarking

bench n expr evaluates expr n times and returns elapsed time.

bench 10 sleep msecs 100
  
1.004674633s

  load "bench/fib.sl"

2.807621686s

  load "bench/fibt.sl"

1.358420848s

codr7 / snabl