minsexp

A (not quite) minimal golang library that reads, evaluates and prints s-expressions. The environment for evaluation can be customized so that minsexp can be used as an embedded language e.g. for a rules engine.

Sample usage

form := "(+ 1 a)"
a := 5
sexp, idx, err := minsexp.Read(form, 0)    // +++++++++++ read form
if err != nil {
  env := make(map[string]interface{}, 2)   // create env map
  env["+"] = StdEnv["+"]                   // borrow "+" fn from standard env
  env["a"] = decimal.NewFromFloat(a)       // bind value (numbers have to be decimals)
  out, err := minsexp.Eval(env, nil, sexp) // +++++++++++ eval sexp
  if err != nil {
    fmt.Println(out)                       // prints "6"
  }
}

Features

there is one built-in special form: let, which binds sequentially (like CL's let*)
many other basic special forms (like and, or, if) and functions (like =, not=, +, <=) can be used
- many basic functions are still missing (string concatenation etc)
there are get and set functions that get or set (public) struct fields
functions, special forms and variables share a single namespace
numbers are of type github.com/shopspring/decimal.Decimal
no support for macros

Symbols of the core library

symbols

nil
true
false

special forms

let (built-in)
do
and
or
if

functions

not
=
not=
compare
<=
<
>=
>
+
-
*
/
get
set

EugenDueck / minsexp