diff options
| -rw-r--r-- | pia/n.lyx | 35 | ||||
| -rw-r--r-- | pia/n4.lyx | 904 | ||||
| -rw-r--r-- | pia/n5.lyx | 106 | ||||
| -rw-r--r-- | pia/n7.lyx | 809 |
4 files changed, 1707 insertions, 147 deletions
@@ -215,6 +215,27 @@ https://www.haskell.org/onlinereport/haskell2010/haskell.html . \end_layout +\begin_layout Itemize +Haskell Wiki. + +\emph on +Monad laws +\emph default +. + Recuperado de +\begin_inset Flex URL +status open + +\begin_layout Plain Layout + +https://wiki.haskell.org/Monad_laws +\end_layout + +\end_inset + + el 5 de diciembre de 2022. +\end_layout + \begin_layout Chapter Introducción \end_layout @@ -315,5 +336,19 @@ filename "n6.lyx" \end_layout +\begin_layout Chapter +Entrada y salida +\end_layout + +\begin_layout Standard +\begin_inset CommandInset include +LatexCommand input +filename "n7.lyx" + +\end_inset + + +\end_layout + \end_body \end_document @@ -359,17 +359,7 @@ reservedop =~ \end_layout \begin_layout Standard -Las variables pueden estar en espacios de nombres jerárquicos: -\begin_inset Note Comment -status open - -\begin_layout Plain Layout -tyvar=varid, tycon=tycls=conid, modid=qtycon=qtycls=qconid -\end_layout - -\end_inset - - +Las variables pueden estar en espacios de nombres aparentemente jerárquicos: \end_layout \begin_layout Standard @@ -411,7 +401,16 @@ qconsym =~ (<conid> \end_layout \begin_layout Standard -Se escriben como sigue: +Realmente sólo se distingue entre el nombre de la variable, detrás del último + +\family typewriter +. +\family default +, y el del módulo, antes del +\family typewriter +. +\family default +, y no hay relación jerárquica entre módulos. \end_layout \begin_layout Standard @@ -904,26 +903,7 @@ contexto nombre. Las expresiones se evalúan en un cierto contexto, y describen un valor que depende de este. - Inicialmente el contexto global incluye las -\series bold -operaciones primitivas -\series default - incluidas en el evaluador, como las operaciones aritméticas básicas y las - incluidas en -\series bold -preludios -\series default -, por defecto el -\series bold -preludio estándar -\series default -, el módulo -\family typewriter -\lang english -Prelude -\family default -\lang spanish -. + \end_layout \begin_layout Standard @@ -1104,6 +1084,16 @@ qconop = gconsym / gconsym = qconsym \end_layout +\begin_layout Plain Layout + +cname = var / con +\end_layout + +\begin_layout Plain Layout + +qop = qvarop / qconop +\end_layout + \end_inset @@ -1128,6 +1118,21 @@ s y una función con nombre normal como operador poniéndola entre comillas Se pueden definir nuevos operadores. \end_layout +\begin_layout Standard +En el resto del capítulo cuando se menciona un nombre concreto, salvo que + se indique lo contrario, se entiende que pertenece al módulo +\family typewriter +\lang english +Prelude +\family default +\lang spanish +, el +\series bold +preludio estándar +\series default +, cuyos vínculos están por defecto en el contexto global. +\end_layout + \begin_layout Section Tipos \end_layout @@ -1206,7 +1211,7 @@ Un tipo puede ser un qconid \family default , cuyo significado depende del entorno, y esta definición puede aceptar - un número fijo de parámetros que también son tipos. + un número fijo de parámetros de tipo. \end_layout \begin_layout Standard @@ -1282,8 +1287,10 @@ polimórfico \begin_layout Standard Tipos primitivos en el \family typewriter +\lang english Prelude \family default +\lang spanish : \end_layout @@ -1519,6 +1526,9 @@ gtycon /= \end_layout \begin_layout Standard +\begin_inset Newpage pagebreak +\end_inset + Podemos definir nuevos tipos para aumentar la seguridad de los programas: \end_layout @@ -1637,8 +1647,10 @@ simpletype . El \family typewriter +\lang english Prelude \family default +\lang spanish define \family typewriter data Bool = False | True @@ -2764,7 +2776,7 @@ a \emph default equivale a \family typewriter -Prelude.negate +negate \emph on a \family default @@ -2791,11 +2803,11 @@ integer \family default equivalen a \family typewriter -Prelude.fromInteger ( +fromInteger ( \emph on x \emph default - :: Prelude.Integer) + :: Integer) \family default , siendo \family typewriter @@ -2809,7 +2821,7 @@ float \family default a \family typewriter -Prelude.fromRational ( +fromRational ( \emph on x \emph default @@ -3837,7 +3849,7 @@ e1 \family default equivale a \family typewriter -Prelude.enumFrom +enumFrom \emph on e1 \family default @@ -3856,7 +3868,7 @@ e2 \family default a \family typewriter -Prelude.enumFromThen +enumFromThen \emph on e1 e2 \family default @@ -3875,7 +3887,7 @@ e3 \family default a \family typewriter -Prelude.enumFromTo +enumFromTo \emph on e1 e3 \family default @@ -3898,7 +3910,7 @@ e3 \family default a \family typewriter -Prelude.enumFromThenTo +enumFromThenTo \emph on e1 e2 e3 \family default @@ -4248,6 +4260,169 @@ e . \end_layout +\begin_layout Standard +\begin_inset listings +inline false +status open + +\begin_layout Plain Layout + +lexp /= +\begin_inset Quotes cld +\end_inset + +do +\begin_inset Quotes crd +\end_inset + + +\begin_inset Quotes cld +\end_inset + +{ +\begin_inset Quotes cld +\end_inset + + stmts +\begin_inset Quotes cld +\end_inset + +} +\begin_inset Quotes crd +\end_inset + + +\end_layout + +\begin_layout Plain Layout + +stmts = *stmt exp [ +\begin_inset Quotes cld +\end_inset + +; +\begin_inset Quotes crd +\end_inset + +] +\end_layout + +\begin_layout Plain Layout + +stmt = (exp / pat +\begin_inset Quotes cld +\end_inset + +<- +\begin_inset Quotes crd +\end_inset + + exp /) +\begin_inset Quotes cld +\end_inset + +; +\begin_inset Quotes crd +\end_inset + + +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard + +\family typewriter +do { +\emph on +exp +\emph default + } +\family default + equivale a +\family typewriter +\emph on +exp +\family default +\emph default +, que debe tener tipo +\family typewriter +m a +\family default + para algún +\family typewriter +m +\family default + de clase +\family typewriter +Monad +\family default + y algún +\family typewriter +a +\family default +; +\family typewriter +do { +\emph on +exp +\emph default +; +\emph on +rest +\emph default + } +\family default + equivale a +\family typewriter +\emph on +exp +\emph default + >> do { +\emph on +rest +\emph default + } +\family default +, y +\family typewriter +do { +\emph on +pat +\emph default + <- +\emph on +exp +\emph default +; +\emph on +rest +\emph default +} +\family default + equivale a +\family typewriter +\emph on +exp +\emph default + >>= +\backslash + +\emph on +pat +\emph default + -> do { +\emph on +rest +\emph default + } +\family default +. +\end_layout + \begin_layout Section Definiciones \end_layout @@ -4550,5 +4725,652 @@ infix ). \end_layout +\begin_layout Section +Módulos +\end_layout + +\begin_layout Standard +\begin_inset listings +inline false +status open + +\begin_layout Plain Layout + +module /= +\begin_inset Quotes cld +\end_inset + +module +\begin_inset Quotes crd +\end_inset + + qconid [exports] +\begin_inset Quotes cld +\end_inset + +where +\begin_inset Quotes crd +\end_inset + + body +\end_layout + +\begin_layout Plain Layout + +exports = +\begin_inset Quotes cld +\end_inset + +( +\begin_inset Quotes cld +\end_inset + + [export *( +\begin_inset Quotes cld +\end_inset + +, +\begin_inset Quotes crd +\end_inset + + export) [ +\begin_inset Quotes cld +\end_inset + +, +\begin_inset Quotes crd +\end_inset + +] +\begin_inset Quotes cld +\end_inset + +) +\begin_inset Quotes crd +\end_inset + + +\end_layout + +\begin_layout Plain Layout + +export = qvar / qconid [ +\begin_inset Quotes cld +\end_inset + +( +\begin_inset Quotes cld +\end_inset + + +\begin_inset Quotes cld +\end_inset + +.. +\begin_inset Quotes crd +\end_inset + + +\begin_inset Quotes cld +\end_inset + +) +\begin_inset Quotes crd +\end_inset + + / +\begin_inset Quotes cld +\end_inset + +( +\begin_inset Quotes cld +\end_inset + + [cname *( +\begin_inset Quotes cld +\end_inset + +, +\begin_inset Quotes crd +\end_inset + + cname)] +\begin_inset Quotes cld +\end_inset + +) +\begin_inset Quotes crd +\end_inset + +] +\end_layout + +\begin_layout Plain Layout + + / qconid [ +\begin_inset Quotes cld +\end_inset + +( +\begin_inset Quotes cld +\end_inset + + +\begin_inset Quotes cld +\end_inset + +.. +\begin_inset Quotes crd +\end_inset + + +\begin_inset Quotes cld +\end_inset + +) +\begin_inset Quotes crd +\end_inset + + / +\begin_inset Quotes cld +\end_inset + +( +\begin_inset Quotes cld +\end_inset + + [qvar *( +\begin_inset Quotes cld +\end_inset + +, +\begin_inset Quotes crd +\end_inset + + qvar)] +\begin_inset Quotes cld +\end_inset + +) +\begin_inset Quotes crd +\end_inset + +] +\end_layout + +\begin_layout Plain Layout + + / +\begin_inset Quotes cld +\end_inset + +module +\begin_inset Quotes crd +\end_inset + + qconid +\end_layout + +\begin_layout Plain Layout + +cname = var / con +\end_layout + +\begin_layout Plain Layout + +body /= +\begin_inset Quotes cld +\end_inset + +{ +\begin_inset Quotes cld +\end_inset + + impdecls [ +\begin_inset Quotes cld +\end_inset + +; +\begin_inset Quotes crd +\end_inset + + topdecls] +\begin_inset Quotes cld +\end_inset + +} +\begin_inset Quotes crd +\end_inset + + +\end_layout + +\begin_layout Plain Layout + +impdecls = impdecl *( +\begin_inset Quotes cld +\end_inset + +; +\begin_inset Quotes crd +\end_inset + + impdecl) +\end_layout + +\begin_layout Plain Layout + +impdecl = +\begin_inset Quotes cld +\end_inset + +import +\begin_inset Quotes crd +\end_inset + + [ +\begin_inset Quotes cld +\end_inset + +qualified +\begin_inset Quotes crd +\end_inset + +] qconid [ +\begin_inset Quotes cld +\end_inset + +as +\begin_inset Quotes crd +\end_inset + + qconid] [impspec] +\end_layout + +\begin_layout Plain Layout + +impspec = [ +\begin_inset Quotes cld +\end_inset + +hiding +\begin_inset Quotes crd +\end_inset + +] +\begin_inset Quotes cld +\end_inset + +( +\begin_inset Quotes cld +\end_inset + + [import *( +\begin_inset Quotes cld +\end_inset + +, +\begin_inset Quotes crd +\end_inset + + import)] +\begin_inset Quotes cld +\end_inset + +) +\begin_inset Quotes crd +\end_inset + + +\end_layout + +\begin_layout Plain Layout + +import = var / qconid[ +\begin_inset Quotes cld +\end_inset + +( +\begin_inset Quotes cld +\end_inset + + +\begin_inset Quotes cld +\end_inset + +.. +\begin_inset Quotes crd +\end_inset + + +\begin_inset Quotes cld +\end_inset + +) +\begin_inset Quotes crd +\end_inset + + / +\begin_inset Quotes cld +\end_inset + +( +\begin_inset Quotes cld +\end_inset + + [cname *( +\begin_inset Quotes cld +\end_inset + +, +\begin_inset Quotes crd +\end_inset + + cname)] +\begin_inset Quotes cld +\end_inset + +) +\begin_inset Quotes crd +\end_inset + + +\end_layout + +\begin_layout Plain Layout + + / qconid[ +\begin_inset Quotes cld +\end_inset + +( +\begin_inset Quotes cld +\end_inset + + +\begin_inset Quotes cld +\end_inset + +.. +\begin_inset Quotes crd +\end_inset + + +\begin_inset Quotes cld +\end_inset + +) +\begin_inset Quotes crd +\end_inset + + / +\begin_inset Quotes cld +\end_inset + +( +\begin_inset Quotes cld +\end_inset + + [var *( +\begin_inset Quotes cld +\end_inset + +, +\begin_inset Quotes crd +\end_inset + + var)] +\begin_inset Quotes cld +\end_inset + +) +\begin_inset Quotes crd +\end_inset + + +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +Haskell organiza los elementos en módulos, uno por fichero, cada uno con + un nombre único y un contexto global formado por los vínculos establecidos + en el módulo y los que se importan de otros. + +\end_layout + +\begin_layout Standard +Una +\series bold +entidad +\series default + es un vínculo importado o exportado por un módulo, con un nombre que no + incluye el nombre del módulo y un valor. +\end_layout + +\begin_layout Standard +Se exportan las entidades indicadas por +\family typewriter +exports +\family default +: +\family typewriter +\emph on +qvar +\family default +\emph default + para una variable, +\family typewriter +\emph on +qconid +\family default +\emph default + para un tipo o clase, +\family typewriter +\emph on +qconid +\emph default +(..) +\family default + para el tipo y todos sus constructores o la clase y todos sus métodos; + +\family typewriter +\emph on +qconid +\emph default +( +\emph on +cname +\emph default +, +\family default +... +\family typewriter +) +\family default + para el tipo y los constructores indicados, y +\family typewriter +\emph on +qconid +\emph default +( +\emph on +qvar +\emph default +, +\family default +... +\family typewriter +) +\family default + para el tipo y los métodos indicados. + Si no hay un +\family typewriter +exports +\family default +, se exportan todos los vínculos definidos en el módulo. +\end_layout + +\begin_layout Standard +Una +\family typewriter +impdecl +\family default + importa entidades del módulo +\family typewriter +qconid +\family default +, por defecto todas las que este importa, pero +\family typewriter +impspec +\family default + permite importar sólo los vínculos de los +\family typewriter +import +\family default +, con la misma semántica que los +\family typewriter +export +\family default +, o sólo los que no están en los +\family typewriter +import +\family default + si se indica +\family typewriter +hiding +\family default +. + Añadir +\family typewriter +qualified +\family default + hace que las entidades se importen con nombre +\family typewriter +\emph on +módulo +\emph default +. +\emph on +entidad +\family default +\emph default +, donde el +\family typewriter +\emph on +módulo +\family default +\emph default + es el nombre del módulo del que se importa o el que se indica después de + +\family typewriter +as +\family default + si aparece. +\end_layout + +\begin_layout Standard +Algunos programadores prefieren usar +\family typewriter +qualified +\family default + en todos los +\family typewriter +import +\family default +, haciendo explícito el origen de cada nombre y usando +\family typewriter +as +\family default + si hace falta para acortar el nombre, mientras que otros prefieren nombres + cortos y usan +\family typewriter +qualified +\family default + o +\family typewriter +hiding +\family default + según sea necesario para evitar conflictos de nombres. +\end_layout + +\begin_layout Standard +Los módulos permiten crear tipos de datos abstractos, pues exportar un tipo + sin constructores hace que este solo se pueda usar fuera del módulo a través + de las operaciones exportadas, permitiendo cambiar la representación del + tipo sin afectar a sus usuarios. +\end_layout + +\begin_layout Standard +Haskell no especifica una relación entre nombres de módulo y de fichero, + pero GHC busca el módulo +\family typewriter +\emph on +A1 +\emph default +. +\family default +... +\family typewriter +. +\emph on +An +\family default +\emph default + en +\family typewriter +\emph on +A1 +\emph default +/ +\family default +... +\family typewriter +/ +\emph on +An +\emph default +.hs +\family default + en el directorio raíz del programa (el directorio actual si se usa GHCi) + y una serie de directorios predefinidos. + +\end_layout + +\begin_layout Standard +Un +\series bold +preludio +\series default + es un módulo que se importa por defecto en los demás como si hubiera un + +\family typewriter +import +\emph on +Preludio +\family default +\emph default +, salvo que haya un +\family typewriter +impdecl +\family default + explícito para ese preludio. + El único es +\family typewriter +\lang english +Prelude +\family default +\lang spanish +, con +\series bold +operaciones primitivas +\series default + incluidas en el evaluador, como las operaciones aritméticas básicas, y + tipos y funciones de utilidad. +\end_layout + \end_body \end_document @@ -1175,7 +1175,6 @@ s \begin_inset Formula $\bot$ \end_inset -. y, cuando se evalúa, imprime el error \family typewriter \emph on @@ -1793,111 +1792,6 @@ type String = [Char] \end_layout -\begin_layout Section -Mónadas -\end_layout - -\begin_layout Standard -\begin_inset Note Comment -status open - -\begin_layout Plain Layout -fail, sequence, sequence_, mapM, mapM_, (=<<) -\end_layout - -\end_inset - - -\end_layout - -\begin_layout Standard -\begin_inset listings -inline false -status open - -\begin_layout Plain Layout - -class Functor f where -\end_layout - -\begin_layout Plain Layout - - fmap :: (a -> b) -> f a -> f b -\end_layout - -\begin_layout Plain Layout - -\end_layout - -\begin_layout Plain Layout - -class Monad m where {#- MINIMAL (>>=), return -#} -\end_layout - -\begin_layout Plain Layout - - (>>=) :: m a -> (a -> m b) -> m b -\end_layout - -\begin_layout Plain Layout - - (>>) :: m a -> m b -> m b -\end_layout - -\begin_layout Plain Layout - - return :: a -> m a -\end_layout - -\begin_layout Plain Layout - -\end_layout - -\begin_layout Plain Layout - - m >> k = m >>= -\backslash -_ -> k -\end_layout - -\begin_layout Plain Layout - -\end_layout - -\begin_layout Plain Layout - -data Either a b = Left a | Right b deriving (Eq, Ord, Read, Show) -\end_layout - -\begin_layout Plain Layout - -data IO a = ... -\end_layout - -\begin_layout Plain Layout - -instance Monad IO where ... -\end_layout - -\end_inset - - -\end_layout - -\begin_layout Standard -\begin_inset Note Comment -status open - -\begin_layout Plain Layout -Maybe, maybe, either, instance Functor IO, instance Monad IO, instance Functor - [], instance Monad [] -\end_layout - -\end_inset - - -\end_layout - \begin_layout Standard \begin_inset Note Note status open diff --git a/pia/n7.lyx b/pia/n7.lyx new file mode 100644 index 0000000..0e78e74 --- /dev/null +++ b/pia/n7.lyx @@ -0,0 +1,809 @@ +#LyX 2.3 created this file. For more info see http://www.lyx.org/ +\lyxformat 544 +\begin_document +\begin_header +\save_transient_properties true +\origin unavailable +\textclass book +\begin_preamble +\input{../defs} +\end_preamble +\use_default_options true +\maintain_unincluded_children false +\language spanish +\language_package default +\inputencoding auto +\fontencoding global +\font_roman "default" "default" +\font_sans "default" "default" +\font_typewriter "default" "default" +\font_math "auto" "auto" +\font_default_family default +\use_non_tex_fonts false +\font_sc false +\font_osf false +\font_sf_scale 100 100 +\font_tt_scale 100 100 +\use_microtype false +\use_dash_ligatures true +\graphics default +\default_output_format default +\output_sync 0 +\bibtex_command default +\index_command default +\paperfontsize default +\spacing single +\use_hyperref false +\papersize default +\use_geometry false +\use_package amsmath 1 +\use_package amssymb 1 +\use_package cancel 1 +\use_package esint 1 +\use_package mathdots 1 +\use_package mathtools 1 +\use_package mhchem 1 +\use_package stackrel 1 +\use_package stmaryrd 1 +\use_package undertilde 1 +\cite_engine basic +\cite_engine_type default +\biblio_style plain +\use_bibtopic false +\use_indices false +\paperorientation portrait +\suppress_date false +\justification true +\use_refstyle 1 +\use_minted 0 +\index Index +\shortcut idx +\color #008000 +\end_index +\secnumdepth 3 +\tocdepth 3 +\paragraph_separation indent +\paragraph_indentation default +\is_math_indent 0 +\math_numbering_side default +\quotes_style french +\dynamic_quotes 0 +\papercolumns 1 +\papersides 1 +\paperpagestyle default +\tracking_changes false +\output_changes false +\html_math_output 0 +\html_css_as_file 0 +\html_be_strict false +\end_header + +\begin_body + +\begin_layout Standard +\begin_inset listings +inline false +status open + +\begin_layout Plain Layout + +class Monad m where {#- MINIMAL (>>=), return -#} +\end_layout + +\begin_layout Plain Layout + + (>>=) :: m a -> (a -> m b) -> m b +\end_layout + +\begin_layout Plain Layout + + (>>) :: m a -> m b -> m b +\end_layout + +\begin_layout Plain Layout + + return :: a -> m a +\end_layout + +\begin_layout Plain Layout + + fail :: String -> m a +\end_layout + +\begin_layout Plain Layout + +\end_layout + +\begin_layout Plain Layout + + m >> k = m >>= +\backslash +_ -> k +\end_layout + +\begin_layout Plain Layout + + fail s = error s +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +\begin_inset Note Comment +status open + +\begin_layout Plain Layout +Functor, sequence, mapM, (=<<), Maybe, maybe, Either, either, instance Functor + IO, instance Monad IO, instance Functor [], instance Monad [], IOError, + ioError, userError, catch, readIO, readLn +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +urldef +\backslash +urlmonada +\backslash +url{https://stackoverflow.com/questions/3870088/a-monad-is-just-a-monoid-in-the-c +ategory-of-endofunctors-whats-the-problem#3870310} +\end_layout + +\begin_layout Plain Layout + + +\backslash +urldef +\backslash +urlmonadb +\backslash +url{http://james-iry.blogspot.com/2009/05/brief-incomplete-and-mostly-wrong.html} +\end_layout + +\begin_layout Plain Layout + + +\backslash +urldef +\backslash +urlmonadc +\backslash +url{https://byorgey.wordpress.com/2009/01/12/abstraction-intuition-and-the-monad-t +utorial-fallacy/} +\end_layout + +\begin_layout Plain Layout + + +\backslash +urldef +\backslash +urlmonadd +\backslash +url{https://blog.plover.com/prog/burritos.html} +\end_layout + +\begin_layout Plain Layout + + +\backslash +urldef +\backslash +urlmonade +\backslash +url{https://wiki.haskell.org/All_About_Monads} +\end_layout + +\begin_layout Plain Layout + + +\backslash +urldef +\backslash +urlmonadf +\backslash +url{https://wiki.haskell.org/Monad} +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +Una +\series bold +mónada +\series default + es una instancia de +\family typewriter +Monad +\family default + con las siguientes propiedades: +\begin_inset Foot +status open + +\begin_layout Plain Layout +Una mónada en +\begin_inset Formula $X$ +\end_inset + + es un monoide en la categoría de los endofuntores de +\begin_inset Formula $X$ +\end_inset + +, con el producto reemplazado por la composición de endofuntores y el conjunto + unidad por el endofuntor identidad ( +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +urlmonada +\end_layout + +\end_inset + +). + Una mónada es un como un burrito ( +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +urlmonadc +\end_layout + +\end_inset + +, +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +urlmonadd +\end_layout + +\end_inset + +). + No voy a explicar la intuición de qué es una mónada porque en el examen + sólo entra la definición formal e IO, pero hay un tutorial muy bueno en + la Wiki de Haskell ( +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +urlmonade +\end_layout + +\end_inset + +) y una explicación resumida ( +\begin_inset ERT +status open + +\begin_layout Plain Layout + + +\backslash +urlmonadf +\end_layout + +\end_inset + +). +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Enumerate +Identidad por la izquierda: +\family typewriter +return a >>= h = ha +\family default +. +\end_layout + +\begin_layout Enumerate +Identidad por la derecha: +\family typewriter +m >>= return = m +\family default +. +\end_layout + +\begin_layout Enumerate +Asociatividad: +\family typewriter +(m >>= g) >>= h = m >>= ( +\backslash +x -> g x >>= h) +\family default +. +\end_layout + +\begin_layout Standard +Una +\series bold +mónada de E/S +\series default + es una mónada +\family typewriter +m +\family default + que además tiene operaciones +\family typewriter +putChar :: Char -> m () +\family default + y +\family typewriter +getChar :: m Char +\family default +, como +\family typewriter +IO +\family default +. + +\family typewriter +IO a +\family default + es el tipo de las acciones que pueden realizar operaciones de E/S y devuelven + un resultado de tipo +\family typewriter +a +\family default +. +\end_layout + +\begin_layout Standard +\begin_inset listings +inline false +status open + +\begin_layout Plain Layout + +data IO a = ... +\end_layout + +\begin_layout Plain Layout + +instance Monad IO where ... +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard + +\family typewriter +return +\emph on +a +\family default +\emph default + es una acción que no hace nada y devuelve +\family typewriter +\emph on +a +\family default +\emph default +, y +\family typewriter +\emph on +m +\emph default + >>= +\emph on +h +\family default +\emph default + es una que ejecuta +\family typewriter +\emph on +m +\family default +\emph default +, le pasa el resultado a +\family typewriter +\emph on +h +\family default +\emph default + y devuelve el resultado de ejecutar la acción devuelta por +\family typewriter +\emph on +h +\family default +\emph default +, permitiendo secuenciar acciones. +\end_layout + +\begin_layout Standard +\begin_inset listings +inline false +status open + +\begin_layout Plain Layout + +sequence_ :: Monad m => [m a] -> m () +\end_layout + +\begin_layout Plain Layout + +sequence_ = foldr (>>) (return ()) +\end_layout + +\begin_layout Plain Layout + +\end_layout + +\begin_layout Plain Layout + +mapM_ :: Monad m => (a -> m b) -> [a] -> m [b] +\end_layout + +\begin_layout Plain Layout + +mapM_ f as = sequence_ (map f as) +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +Podemos definir (aunque no está en el +\family typewriter +Prelude +\family default +): +\begin_inset Foot +status open + +\begin_layout Plain Layout +Está en +\family typewriter +Control.Monad.Extra +\family default + y se llama +\family typewriter +skip +\family default +. +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +\begin_inset listings +inline false +status open + +\begin_layout Plain Layout + +done :: Monad m => m () +\end_layout + +\begin_layout Plain Layout + +done = return () +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard + +\family typewriter +putChar +\family default + imprime un caracter, +\family typewriter +getChar +\family default + lee uno de la entrada estándar y +\family typewriter +getContents +\family default + lee toda la entrada estándar en una +\family typewriter +String +\family default + de forma perezosa según se va necesitando. +\end_layout + +\begin_layout Standard +\begin_inset listings +inline false +status open + +\begin_layout Plain Layout + +putChar :: Char -> IO () +\end_layout + +\begin_layout Plain Layout + +putChar = ... +\end_layout + +\begin_layout Plain Layout + +\end_layout + +\begin_layout Plain Layout + +getChar :: IO Char +\end_layout + +\begin_layout Plain Layout + +getChar = ... +\end_layout + +\begin_layout Plain Layout + +\end_layout + +\begin_layout Plain Layout + +getContents :: IOString +\end_layout + +\begin_layout Plain Layout + +getContents = ... +\end_layout + +\begin_layout Plain Layout + +\end_layout + +\begin_layout Plain Layout + +putStr, putStrLn :: String -> IO () +\end_layout + +\begin_layout Plain Layout + +putStr s = map_ putChar s +\end_layout + +\begin_layout Plain Layout + +putStrLn s = putStr s >> putStr +\begin_inset Quotes cld +\end_inset + + +\backslash +n +\begin_inset Quotes crd +\end_inset + + +\end_layout + +\begin_layout Plain Layout + +\end_layout + +\begin_layout Plain Layout + +print :: Show a => a -> IO () +\end_layout + +\begin_layout Plain Layout + +print x = putStrLn (show x) +\end_layout + +\begin_layout Plain Layout + +\end_layout + +\begin_layout Plain Layout + +getLine :: IO String +\end_layout + +\begin_layout Plain Layout + +getLine = getChar >>= +\backslash +c -> if c == ' +\backslash +n' then return +\begin_inset Quotes cld +\end_inset + + +\begin_inset Quotes crd +\end_inset + + +\end_layout + +\begin_layout Plain Layout + + else getLine >>= +\backslash +s -> return (c:s) +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard + +\family typewriter +interact +\emph on +f +\family default +\emph default + desactiva el +\emph on +buffering +\emph default + de la entrada y salida estándar, le pasa la entrada estándar a +\family typewriter +\emph on +f +\family default +\emph default + y va imprimiendo el valor devuelto por la función, evaluándolo y pidiendo + caracteres de la entrada según sea necesario. +\end_layout + +\begin_layout Standard +\begin_inset listings +inline false +status open + +\begin_layout Plain Layout + +interact :: (String -> String) -> IO () +\end_layout + +\begin_layout Plain Layout + +interact f = hSetBuffering stdin NoBuffering >>= +\end_layout + +\begin_layout Plain Layout + + hSetBuffering stdout NoBuffering >>= +\end_layout + +\begin_layout Plain Layout + + s <- getContents >>= putStr (f s) +\end_layout + +\begin_layout Plain Layout + + where hSetBuffering = ... +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +\begin_inset Newpage pagebreak +\end_inset + + +\end_layout + +\begin_layout Standard + +\family typewriter +readFile +\family default + lee el contenido de un fichero de forma perezosa, +\family typewriter +writeFile +\family default + escribe un fichero y +\family typewriter +appendFile +\family default + añade contenido al final de uno. +\end_layout + +\begin_layout Standard +\begin_inset listings +inline false +status open + +\begin_layout Plain Layout + +type FilePath = String +\end_layout + +\begin_layout Plain Layout + +readFile :: FilePath -> IO String +\end_layout + +\begin_layout Plain Layout + +readFile = ... +\end_layout + +\begin_layout Plain Layout + +\end_layout + +\begin_layout Plain Layout + +writeFile, appendFile :: FilePath -> String -> IO () +\end_layout + +\begin_layout Plain Layout + +writeFile = ... +\end_layout + +\begin_layout Plain Layout + +appendFile = ... +\end_layout + +\end_inset + + +\end_layout + +\begin_layout Standard +Un programa en Haskell es una colección de módulos de los que uno es el + principal y tiene un vínculo +\family typewriter +main :: IO () +\family default +, que se ejecuta al ejecutar el programa. +\end_layout + +\end_body +\end_document |