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Diffstat (limited to 'v2/src/content/pt')
| -rw-r--r-- | v2/src/content/pt/hea/condicional-ternario-lisp.md | 65 | ||||
| -rw-r--r-- | v2/src/content/pt/pastebin/exercicios-sicp-e-19.md | 105 | ||||
| -rw-r--r-- | v2/src/content/pt/sobre.page | 7 |
3 files changed, 0 insertions, 177 deletions
diff --git a/v2/src/content/pt/hea/condicional-ternario-lisp.md b/v2/src/content/pt/hea/condicional-ternario-lisp.md deleted file mode 100644 index 6971827..0000000 --- a/v2/src/content/pt/hea/condicional-ternario-lisp.md +++ /dev/null @@ -1,65 +0,0 @@ ---- - -title: Three-way conditional for number signs on Lisp - -date: 2021-04-24 3 - -update: 2021-08-14 - -categories: lisp scheme common-lisp - ---- - -A useful macro from Paul Graham's [On Lisp][on-lisp] book: - -```lisp -(defmacro nif (expr pos zero neg) - (let ((g (gensym))) - `(let ((,g ,expr)) - (cond ((plusp ,g) ,pos) - ((zerop ,g) ,zero) - (t ,neg))))) -``` - -After I looked at this macro, I started seeing opportunities to using it in -many places, and yet I didn't see anyone else using it. - -The latest example I can think of is section 1.3.3 of [Structure and -Interpretation of Computer Programs][sicp], which I was reading recently: - -```scheme -(define (search f neg-point pos-point) - (let ((midpoint (average neg-point pos-point))) - (if (close-enough? neg-point post-point) - midpoint - (let ((test-value (f midpoint))) - (cond ((positive? test-value) - (search f neg-point midpoint)) - ((negative? test-value) - (search f midpoint pos-point)) - (else midpoint)))))) -``` - -Not that the book should introduce such macro this early, but I couldn't -avoid feeling bothered by not using the `nif` macro, which could even remove -the need for the intermediate `test-value` variable: - -```scheme -(define (search f neg-point pos-point) - (let ((midpoint (average neg-point pos-point))) - (if (close-enough? neg-point post-point) - midpoint - (nif (f midpoint) - (search f neg-point midpoint) - (midpoint) - (search f midpoint pos-point))))) -``` - -It also avoids `cond`'s extra clunky parentheses for grouping, which is -unnecessary but built-in. - -As a macro, I personally feel it tilts the balance towards expressivenes -despite its extra cognitive load toll. - -[on-lisp]: http://www.paulgraham.com/onlisptext.html [sicp]: -https://mitpress.mit.edu/sites/default/files/sicp/index.html diff --git a/v2/src/content/pt/pastebin/exercicios-sicp-e-19.md b/v2/src/content/pt/pastebin/exercicios-sicp-e-19.md deleted file mode 100644 index 89dacfd..0000000 --- a/v2/src/content/pt/pastebin/exercicios-sicp-e-19.md +++ /dev/null @@ -1,105 +0,0 @@ ---- - -title: SICP exercise 3.19 - -date: 2021-09-02 - -categories: lisp programming-languages - ---- - -Some content here, before: - -```scheme -(define (cycle? l) - (define (rec l x) - (cond - ((null? x) false) - ((eq? l x) true) - (true (rec l (cdr x))))) - (rec l (cdr l))) -``` - -Sample interactive session: - -```scheme -scheme@(guile-user)> (define true #t) -scheme@(guile-user)> (define false #f) -scheme@(guile-user)> -(define (cycle? l) - (define (rec l x) - (cond - ((null? x) false) - ((eq? l x) true) - (true (rec l (cdr x))))) - (rec l (cdr l))) -scheme@(guile-user)> (cycle? '(1 2 3)) -$9 = #f -scheme@(guile-user)> (cycle? (make-cycle '(1 2 3))) -$10 = #t -``` - -# An h1 - -a list: - -1. one -2. two -3. three - -some content. - -- item -- another -- yet another - -## An h2 - -Xablau: - -``` xupliu 1 - -3 4 - - - - - -dez ``` - -Foi `wikiwiu`. - -a very long code block: - -``` -wef -wef wef wef wef -wef wef wef wef we fwef wef wef wef wef -``` - -Someone said: - -> Xablau, xupliu. - -### A repeated header ### A repeated header - -a big list: - -1. a -1. a -1. a -1. a -1. a -1. a -1. a -1. a -1. a -1. a -1. a -1. a -1. a -1. a -1. a -1. a -1. a -1. a diff --git a/v2/src/content/pt/sobre.page b/v2/src/content/pt/sobre.page deleted file mode 100644 index aac3e67..0000000 --- a/v2/src/content/pt/sobre.page +++ /dev/null @@ -1,7 +0,0 @@ ---- - -title: About - ---- - -It's all about me, baby! |