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koans, stuff

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dice - more practice with signal and clog
backquote - first practice with @,a splicing
macros - some news of common errors:
- capturing outer symbols, so caller expects them to be used, but
invisible internal values take their place
- evaluating "pass by name" forms too many times
- evaluating them in surprising order
This commit is contained in:
efim
2022-08-19 08:38:50 +00:00
parent cdeeb2fead
commit 063c5c52d1
4 changed files with 148 additions and 95 deletions
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37
lisp-koans/koans/backquote.lisp
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@@ -19,23 +19,26 @@
(let ((x '(123))
(z '(7 8 9)))
;; ' quotes an expression normally.
(assert-equal ____ '(x 45 6 z))
(assert-equal (list 'x 45 6 'z) '(x 45 6 z))
;; ` backquotes an expression; without any unquotes, it is equivalent to
;; using the normal quote.
(assert-equal ____ `(x 45 6 z))
(assert-equal '(x 45 6 z) `(x 45 6 z))
;; , unquotes a part of the expression.
(assert-equal ____ `(,x 45 6 z))
(assert-equal ____ `(,x 45 6 ,z))
(assert-equal '((123) 45 6 z) `(,x 45 6 z))
(assert-equal '((123) 45 6 (7 8 9)) `(,x 45 6 ,z))
;; ,@ splices an expression into the into the list surrounding it.
(assert-equal ____ `(,x 45 6 ,@z))
(assert-equal ____ `(,@x 45 6 ,@z))))
(assert-equal '((123) 45 6 7 8 9) `(,x 45 6 ,@z))
(assert-equal '(123 45 6 7 8 9) `(,@x 45 6 ,@z))))
(define-test backquote-forms
;; Because of its properties, backquote is useful for constructing Lisp forms
;; that are macroexpansions or parts of macroexpansions.
(let ((variable 'x))
;; Fill in the blank without without using backquote/unquote notation.
(assert-equal ____
(assert-equal '(if (typep x 'string)
(format nil "The value of ~A is ~A" 'x x)
(error 'type-error :datum x
:expected-type 'string))
`(if (typep ,variable 'string)
(format nil "The value of ~A is ~A" ',variable ,variable)
(error 'type-error :datum ,variable
@@ -43,7 +46,9 @@
(let ((error-type 'type-error)
(error-arguments '(:datum x :expected-type 'string)))
;; Fill in the blank without without using backquote/unquote notation.
(assert-equal ____
(assert-equal '(if (typep x 'string)
(format nil "The value of ~A is ~A" 'x x)
(error 'type-error :datum x :expected-type 'string))
`(if (typep x 'string)
(format nil "The value of ~A is ~A" 'x x)
(error ',error-type ,@error-arguments)))))
@@ -51,15 +56,15 @@
(define-test numbers-and-words
(let ((number 5)
(word 'dolphin))
(true-or-false? ____ (equal '(1 3 5) `(1 3 5)))
(true-or-false? ____ (equal '(1 3 5) `(1 3 number)))
(assert-equal ____ `(1 3 ,number))
(assert-equal _____ `(word ,word ,word word))))
(true-or-false? t (equal '(1 3 5) `(1 3 5)))
(true-or-false? nil (equal '(1 3 5) `(1 3 number)))
(assert-equal '(1 3 5) `(1 3 ,number))
(assert-equal '(word dolphin dolphin word) `(word ,word ,word word))))
(define-test splicing
(let ((axis '(x y z)))
(assert-equal '(the axis are ____) `(the axis are ,axis))
(assert-equal '(the axis are ____) `(the axis are ,@axis)))
(assert-equal '(the axis are (x y z)) `(the axis are ,axis))
(assert-equal '(the axis are x y z) `(the axis are ,@axis)))
(let ((coordinates '((43.15 77.6) (42.36 71.06))))
(assert-equal ____ `(the coordinates are ,coordinates))
(assert-equal ____ `(the coordinates are ,@coordinates))))
(assert-equal '(the coordinates are ((43.15 77.6) (42.36 71.06))) `(the coordinates are ,coordinates))
(assert-equal '(the coordinates are (43.15 77.6) (42.36 71.06)) `(the coordinates are ,@coordinates))))