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Stak Scheme

Multiple values

Pass multiple values to a continuation

Given a file named “main.scm” with:

(import (scheme base))


(write-u8
  (call-with-values
    (lambda () (values 1 4 60))
    (lambda (x y z) (+ x y z))))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Call call-with-values with a value

Given a file named “main.scm” with:

(import (scheme base))


(write-u8 (+ 66 (call-with-values * -)))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

define-values

Define no value

Given a file named “main.scm” with:

(import (scheme base))


(define-values () (values))

When I successfully run stak main.scm

Then the exit status should be 0.

Define a value

Given a file named “main.scm” with:

(import (scheme base))


(define-values (x) (values 65))


(write-u8 x)

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Define multiple values

Given a file named “main.scm” with:

(import (scheme base))


(define-values (x y z) (values 65 66 67))


(write-u8 x)
(write-u8 y)
(write-u8 z)

When I successfully run stak main.scm

Then the stdout should contain exactly “ABC”.

Define a list from values

Given a file named “main.scm” with:

(import (scheme base) (scheme cxr))


(define-values xs (values 65 66 67))


(write-u8 (car xs))
(write-u8 (cadr xs))
(write-u8 (caddr xs))

When I successfully run stak main.scm

Then the stdout should contain exactly “ABC”.

Define values and a list from values

Given a file named “main.scm” with:

(import (scheme base))


(define-values (x . xs) (values 65 66 67))


(write-u8 x)
(write-u8 (car xs))
(write-u8 (cadr xs))

When I successfully run stak main.scm

Then the stdout should contain exactly “ABC”.

Define values in a definition

Given a file named “main.scm” with:

(import (scheme base))


(define (f)
  (values 60 5))


(define (g)
  (define-values (x y) (f))
  (+ x y))


(write-u8 (g))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Define values in a definition multiple times

Given a file named “main.scm” with:

(import (scheme base))


(define (f x)
  (values 65 x))


(define (g)
  (define-values (x y) (f 0))
  (define-values (v w) (f 1))


  (write-u8 (+ x y))
  (write-u8 (+ v w)))


(g)

When I successfully run stak main.scm

Then the stdout should contain exactly “AB”.

Define values in a definition multiple times sequentially

Given a file named “main.scm” with:

(import (scheme base))


(define (f x)
  (values 65 x))


(define (g)
  (define-values (x y) (f 0))
  (define-values (v w) (f (+ y 1)))


  (write-u8 (+ x y))
  (write-u8 (+ v w)))


(g)

When I successfully run stak main.scm

Then the stdout should contain exactly “AB”.

let-values

Define no value

Given a file named “main.scm” with:

(import (scheme base))


(let-values ((() (values)))
  #f)

When I successfully run stak main.scm

Then the exit status should be 0.

Define a value

Given a file named “main.scm” with:

(import (scheme base))


(let-values (((x) (values 65)))
  (write-u8 x))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Define multiple values

Given a file named “main.scm” with:

(import (scheme base))


(let-values (((x y z) (values 65 66 67)))
  (write-u8 x)
  (write-u8 y)
  (write-u8 z))

When I successfully run stak main.scm

Then the stdout should contain exactly “ABC”.

Define a list from values

Given a file named “main.scm” with:

(import (scheme base) (scheme cxr))


(let-values ((xs (values 65 66 67)))
  (write-u8 (car xs))
  (write-u8 (cadr xs))
  (write-u8 (caddr xs)))

When I successfully run stak main.scm

Then the stdout should contain exactly “ABC”.

Define values and a list from values

Given a file named “main.scm” with:

(import (scheme base))


(let-values (((x . xs) (values 65 66 67)))
  (write-u8 x)
  (write-u8 (car xs))
  (write-u8 (cadr xs)))

When I successfully run stak main.scm

Then the stdout should contain exactly “ABC”.