Evaluation

Import an eval library

Given a file named “main.scm” with:

(import (scheme eval))

When I successfully run stak main.scm

Then the exit status should be 0.

Evaluate false

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(write-u8 (if (eval #f (environment)) 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “B”.

Evaluate a number

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(write-u8 (eval 65 (environment)))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Evaluate a string

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(write-string (eval "foo" (environment)))

When I successfully run stak main.scm

Then the stdout should contain exactly “foo”.

Use an environment

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(write-u8 (eval 65 (environment '(scheme base))))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Use two environments

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(write-u8 (eval 65 (environment '(scheme base) '(scheme write))))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Use an interaction environment

Given a file named “main.scm” with:

(import (scheme base) (scheme eval) (scheme repl))

(write-u8 (eval 65 (interaction-environment)))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Define variables in an interaction environment

Given a file named “main.scm” with:

(import (scheme base) (scheme eval) (scheme repl))

(eval '(import (scheme base)) (interaction-environment))
(eval '(define x 42) (interaction-environment))
(eval '(define y 23) (interaction-environment))
(write-u8 (eval '(+ x y) (interaction-environment)))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Environment

Use a define syntax with a variable

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(eval
  '(begin
    (define x 65)
    (write-u8 x))
  (environment '(scheme base)))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Use a define syntax with a procedure

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(eval
  '(begin
    (define (f x)
      (+ x 65))
    (write-u8 (f 1)))
  (environment '(scheme base)))

When I successfully run stak main.scm

Then the stdout should contain exactly “B”.

Do not access outer environment

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(define x #t)

(eval
  '(unless x (error "Oh, no!"))
  (environment '(scheme base)))

When I run stak main.scm

Then the exit status should not be 0.

Do not corrupt outer environment

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(define x 65)

(eval
  '(begin (define x 66))
  (environment '(scheme base)))

(write-u8 x)

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Procedures

Use a + procedure

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(write-u8 (eval '(+ 60 5) (environment '(scheme base))))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Use a display procedure

Given a file named “main.scm” with:

(import (scheme base) (scheme eval) (scheme write))

(eval '(display "foo") (environment '(scheme write)))

When I successfully run stak main.scm

Then the stdout should contain exactly “foo”.

Use a set! procedure

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(write-u8
  (eval
    '(let ((x 0))
      (set! x 65)
      x)
    (environment '(scheme base))))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Syntaxes

Use a begin syntax

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(write-u8
  (eval
    '(begin 42 65)
    (environment '(scheme base))))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Use an if syntax

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(eval '(write-u8 (if <value> 65 66)) (environment '(scheme base)))

When I successfully run stak main.scm

Then the stdout should contain exactly “<output>”.

Examples

value	output
#f	B
#t	A

Use a lambda syntax with no argument

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(write-u8
  (eval
    '((lambda () 65))
    (environment '(scheme base))))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Use a lambda syntax with an argument

Given a file named “main.scm” with:

(import (scheme base) (scheme eval))

(write-u8
  (eval
    '((lambda (x) x) 65)
    (environment '(scheme base))))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.