{"id":7565,"date":"2022-12-12T06:00:40","date_gmt":"2022-12-12T04:00:40","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=7565"},"modified":"2023-04-20T17:23:55","modified_gmt":"2023-04-20T15:23:55","slug":"12-dic-22","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/12-dic-22\/","title":{"rendered":"El tipo de las expresiones aritm\u00e9ticas: Valor de una expresi\u00f3n"},"content":{"rendered":"<p>Usando el <a href=\"https:\/\/bit.ly\/40vCQUh\">tipo de las expresiones aritm\u00e9ticas<\/a>, definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   valor :: Expr -> Int\n<\/pre>\n<p>tal que <code>valor e<\/code> es el valor de la expresi\u00f3n <code>e<\/code> (donde el valor de <code>SiCero e e1 e2<\/code> es el valor de <code>e1<\/code> si el valor de <code>e<\/code> es cero y el es el valor de <code>e2<\/code>, en caso contrario). Por ejemplo,<\/p>\n<pre lang=\"text\">\n   valor (Op (Suma (Lit 3) (Lit 5)))      ==  -8\n   valor (SiCero (Lit 0) (Lit 4) (Lit 5)) == 4\n   valor (SiCero (Lit 1) (Lit 4) (Lit 5)) == 5\n<\/pre>\n<hr \/>\n<p><b>Soluciones<\/b><\/p>\n<p>A continuaci\u00f3n se muestran las <a href=\"#haskell\">soluciones en Haskell<\/a> y las <a href=\"#python\">soluciones en Python<\/a>.<\/p>\n<p><a name=\"haskell\"><\/a><br \/>\n<b>Soluciones en Haskell<\/b><\/p>\n<pre lang=\"haskell\">\nimport Tipo_expresion_aritmetica (Expr (..))\n\nvalor :: Expr -> Int\nvalor (Lit n)        = n\nvalor (Suma x y)     = valor x + valor y\nvalor (Op x)         = - valor x\nvalor (SiCero x y z) | valor x == 0 = valor y\n                     | otherwise    = valor z\n<\/pre>\n<p><a name=\"python\"><\/a><br \/>\n<b>Soluciones en Python<\/b><\/p>\n<pre lang=\"python\">\nfrom src.tipo_expresion_aritmetica import Expr, Lit, Op, SiCero, Suma\n\n# 1\u00aa soluci\u00f3n\n# ===========\n\ndef valor(e: Expr) -> int:\n    match e:\n        case Lit(n):\n            return n\n        case Suma(x, y):\n            return valor(x) + valor(y)\n        case Op(x):\n            return -valor(x)\n        case SiCero(x, y, z):\n            return valor(y) if valor(x) == 0 else valor(z)\n    assert False\n\n# 2\u00aa soluci\u00f3n\n# ===========\n\ndef valor2(e: Expr) -> int:\n    if isinstance(e, Lit):\n        return e.x\n    if isinstance(e, Suma):\n        return valor2(e.x) + valor2(e.y)\n    if isinstance(e, Op):\n        return -valor2(e.x)\n    if isinstance(e, SiCero):\n        if valor2(e.x) == 0:\n            return valor2(e.y)\n        return valor2(e.z)\n    assert False\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Usando el tipo de las expresiones aritm\u00e9ticas, definir la funci\u00f3n valor :: Expr -> Int tal que valor e es el valor de la expresi\u00f3n e (donde el valor de SiCero e e1 e2 es el valor de e1 si el valor de e es cero y el es el valor de e2, en caso&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"footnotes":"","_jetpack_memberships_contains_paid_content":false},"categories":[581],"tags":[582],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7565"}],"collection":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/comments?post=7565"}],"version-history":[{"count":6,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7565\/revisions"}],"predecessor-version":[{"id":8079,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7565\/revisions\/8079"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=7565"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=7565"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=7565"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}