Docs

eval

Form

(eval expr)

eval compiles and executes expr at runtime.

Evaluation uses the current lexical environment first, then global bindings and builtins.

`expr`	Result
Number, string, boolean, and other self-evaluating values	Returned unchanged
Symbol	Resolved in current lexical scope, then globals/builtins
List or pair	Compiled and evaluated as code
Other heap values	Returned unchanged

Error behavior

Runtime errors raised while executing eval code preserve their existing tags (for example runtime.type-error).
User-raised tags preserve their original symbol.
Compile-path failures are reported as runtime.user-error with diagnostic text.
There is no eval-error wrapper tag.

Examples

(eval '(+ 1 2))                           ; => 3
(let ((x 10)) (eval '(+ x 5)))           ; => 15
(let ((x 10))
  (let ((f (lambda (y) (eval '(+ x y)))))
    (f 7)))                               ; => 17

Runtime tag preservation:

(catch 'runtime.type-error
  (eval '(car 1)))

User tag preservation:

(catch 'my-tag
  (eval '(raise 'my-tag 7)))

Notes

eval is a builtin and is available without importing a module.
Reentrant calls are supported (calling eval from inside running functions is valid).