Macro

Match a rule

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ x)
      x)))

(write-u8 (foo 65))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Match rules

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ x)
      x)
    ((_ x y)
      y)))

(write-u8 (foo 65 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “B”.

Match a nested pattern

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax my-cond
  (syntax-rules (else)
    ((_ (condition then-result) (else else-result))
      (if condition then-result else-result))))

(write-u8
  (my-cond
    (#t
      65)
    (else
      66)))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Capture a free variable

Given a file named “main.scm” with:

(import (scheme base))

(define x 65)

(define-syntax modify
  (syntax-rules ()
    ((_)
      (set! x 66))))

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

(modify)
(write-u8 x)

When I successfully run stak main.scm

Then the stdout should contain exactly “AB”.

Match an ellipsis pattern

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ x ...)
      (x ...))))

(foo write-u8 65)

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Match a preceding ellipsis pattern

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ x ... y)
      (y x ...))))

(foo 65 write-u8)

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Match a succeeding ellipsis pattern

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ x y ...)
      (x y ...))))

(foo write-u8 65)

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Match an ellipsis pattern with an empty list

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ x ...)
      (write-u8 65 x ...))))

(foo)

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Match a nested ellipsis pattern

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ (x ...) ...)
      (begin (x ...) ...))))

(foo (write-u8 65) (write-u8 66 (current-output-port)))

When I successfully run stak main.scm

Then the stdout should contain exactly “AB”.

Match a deeply nested ellipsis pattern

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ ((x ...) ...) ...)
      (begin (begin (x ...) ...) ...))))

(foo
  ((write-u8 65))
  ((write-u8 66) (write-u8 67 (current-output-port))))

When I successfully run stak main.scm

Then the stdout should contain exactly “ABC”.

Expand an ellipsis pattern

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ (x y) ...)
      (begin (x y) ...))))

(foo
  (write-u8 65)
  (write-char #\B))

When I successfully run stak main.scm

Then the stdout should contain exactly “AB”.

Match a custom ellipsis pattern

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules many ()
    ((_ x many)
      (x many))))

(foo write-u8 65)

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Match two ellipses at different levels

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax plus
  (syntax-rules ()
    ((_ (x y ...) v w ...)
      (+ x v))))

(write-u8
  (plus
    (60 "foo")
    5
    "bar"))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Match an improper list

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ (x . y))
      y)))

(write-u8 (foo (65 . 66)))

When I successfully run stak main.scm

Then the stdout should contain exactly “B”.

Match an ellipsis pattern and an improper list

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ (x ... . y))
      y)))

(write-u8 (foo (65 66 . 67)))

When I successfully run stak main.scm

Then the stdout should contain exactly “C”.

Expand an empty ellipsis pattern and an improper list

Given a file named “main.scm” with:

(import (scheme base) (scheme write))

(define-syntax foo
  (syntax-rules ()
    ((_ (x y ... . z))
      '(y ... . z))))

(write-u8 (foo (65 . 66)))

When I successfully run stak main.scm

Then the stdout should contain exactly “B”.

Match an ellipsis pattern to an improper list

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ (x y ...))
      #f)))

(foo (1 . 2))

When I run stak main.scm

Then the exit status should not be 0.

Expand an ellipsis pattern of an improper list

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ (x . y) ...)
      (begin (define (x . y) y) ...))))

(foo (f . x))

(for-each write-u8 (f 65 66 67))

When I successfully run stak main.scm

Then the stdout should contain exactly “ABC”.

Expand a list with an ellipsis pattern

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ x)
      (x ...))))

(foo (write-u8 65))

When I run stak main.scm

Then the exit status should not be 0.

Expand ellipsis and singleton patterns

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ x y ...)
      (begin (x y) ...))))

(foo write-u8 65 66 67)

When I successfully run stak main.scm

Then the stdout should contain exactly “ABC”.

Match a literal identifier

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax my-if
  (syntax-rules (then else)
    ((_ x then y else z)
      (if x y z))))

(write-u8 (my-if #f then 65 else 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “B”.

Expand a macro recursively

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_) (foo 65))
    ((_ x) x)
    ((_ x y) (foo))))

(write-u8 (foo))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Expand a spread variable with a constant

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ x ...)
      (let ((x #f) ...)
        65))))

(write-u8 (foo x y z))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Throw an error if no rule matches

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_) #f)))

(foo 42)

When I run stak main.scm

Then the exit status should not be 0.

Define a recursive local macro in a body

Given a file named “main.scm” with:

(import (scheme base))

(let ()
  (define-syntax foo
    (syntax-rules ()
      ((_ x)
        x)
      ((_ x y)
        (foo y))))

  (write-u8 (foo 65 66)))

When I successfully run stak main.scm

Then the stdout should contain exactly “B”.

Define a mutually recursive local macro in a body

Given a file named “main.scm” with:

(import (scheme base))

(let ()
  (define-syntax foo
    (syntax-rules ()
      ((_ x)
        x)
      ((_ x ... y)
        (bar x ...))))

  (define-syntax bar
    (syntax-rules ()
      ((_ x)
        x)
      ((_ x ... y)
        (foo x ...))))

  (write-u8 (foo 65 66 67)))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Shadow a global value by a global macro

Given a file named “main.scm” with:

(import (scheme base))

(define foo 42)

(define-syntax foo
  (syntax-rules ()
    ((_ x)
      x)))

(write-u8 (foo 65))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Use a global macro as a shadowed value

Given a file named “main.scm” with:

(import (scheme base))

(define foo 65)

(define-syntax foo
  (syntax-rules ()
    ((_ x)
      x)))

(write-u8 foo)

When I run stak main.scm

Then the exit status should not be 0.

Shadow a global macro by a global value

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_ x)
      x)))

(define foo 65)

(write-u8 foo)

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Shadow a literal by a global value

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules (bar)
    ((_ bar x)
      x)))

(define bar #f)

(write-u8 (foo bar 65))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Shadow a literal by a local value

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules (bar)
    ((_ bar x)
      x)))

(let ((bar #f))
  (write-u8 (foo bar 65)))

When I run stak main.scm

Then the exit status should not be 0.

Use a macro as a value

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax foo
  (syntax-rules ()
    ((_)
      65)))

foo

When I run stak main.scm

Then the exit status should not be 0.

Resolve denotations recursively

Given a file named “main.scm” with:

(import (scheme base))

(define (id x)
  x)

(define-syntax foo
  (syntax-rules ()
    ((_ y)
      (let ((x 65)) y))))

(define (bar x)
  (foo (id x)))

(write-u8 (bar 66))

When I successfully run stak main.scm

Then the stdout should contain exactly “B”.

Bind the same name as a global value

Given a file named “main.scm” with:

(import (scheme base))

(define x 42)

(define-syntax foo
  (syntax-rules ()
    ((_ y)
      (let ((x y)) x))))

(write-u8 (foo 65))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Bind the same name as a global macro

Given a file named “main.scm” with:

(import (scheme base))

(define-syntax x
   (syntax-rules ()
      ((_) 42)))

(define-syntax foo
  (syntax-rules ()
    ((_ y)
      (let ((x y)) x))))

(write-u8 (foo 65))

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Re-define define-syntax

Given a file named “main.scm” with:

(import (scheme base))

(define define-syntax 65)

(write-u8 define-syntax)

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Re-define ...

Given a file named “main.scm” with:

(import (scheme base))

(define ... 65)

(write-u8 ...)

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.

Define _

Given a file named “main.scm” with:

(import (scheme base))

(define _ 65)

(write-u8 _)

When I successfully run stak main.scm

Then the stdout should contain exactly “A”.