3089 lines
79 KiB
Plaintext
3089 lines
79 KiB
Plaintext
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"</style><div class=\"suggestion-name\" style=\"clear:both;\">Unused LANGUAGE pragma</div><div class=\"suggestion-row\" style=\"float: left;\"><div class=\"suggestion-warning\">Found:</div><div class=\"highlight-code\" id=\"haskell\">{-# LANGUAGE TemplateHaskell #-}</div></div><div class=\"suggestion-row\" style=\"float: left;\"><div class=\"suggestion-warning\">Why Not:</div><div class=\"highlight-code\" id=\"haskell\"></div></div><div class=\"suggestion-name\" style=\"clear:both;\">Unused LANGUAGE pragma</div><div class=\"suggestion-row\" style=\"float: left;\"><div class=\"suggestion-warning\">Found:</div><div class=\"highlight-code\" id=\"haskell\">{-# LANGUAGE TypeApplications #-}</div></div><div class=\"suggestion-row\" style=\"float: left;\"><div class=\"suggestion-warning\">Why Not:</div><div class=\"highlight-code\" id=\"haskell\"></div></div><div class=\"suggestion-name\" style=\"clear:both;\">Unused LANGUAGE pragma</div><div class=\"suggestion-row\" style=\"float: left;\"><div class=\"suggestion-warning\">Found:</div><div class=\"highlight-code\" id=\"haskell\">{-# LANGUAGE OverloadedStrings #-}</div></div><div class=\"suggestion-row\" style=\"float: left;\"><div class=\"suggestion-warning\">Why Not:</div><div class=\"highlight-code\" id=\"haskell\"></div></div>"
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"Line 1: Unused LANGUAGE pragma\n",
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"Found:\n",
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"{-# LANGUAGE TemplateHaskell #-}\n",
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"Why not:\n",
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"Line 6: Unused LANGUAGE pragma\n",
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"Found:\n",
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"{-# LANGUAGE TypeApplications #-}\n",
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"Why not:\n",
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"Line 9: Unused LANGUAGE pragma\n",
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"Found:\n",
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"{-# LANGUAGE OverloadedStrings #-}\n",
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"Why not:"
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||
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],
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"source": [
|
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"{-# LANGUAGE TemplateHaskell #-}\n",
|
||
"{-# LANGUAGE FlexibleInstances #-}\n",
|
||
"{-# LANGUAGE FlexibleContexts #-}\n",
|
||
"{-# LANGUAGE RankNTypes #-}\n",
|
||
"{-# LANGUAGE ScopedTypeVariables #-}\n",
|
||
"{-# LANGUAGE TypeApplications #-}\n",
|
||
"{-# LANGUAGE TypeFamilies #-}\n",
|
||
"{-# LANGUAGE InstanceSigs #-}\n",
|
||
"{-# LANGUAGE OverloadedStrings #-}\n",
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||
"{-# LANGUAGE AllowAmbiguousTypes #-}\n",
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||
"\n",
|
||
"import Control.Lens\n",
|
||
"import Numeric.Lens\n",
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"import Data.Bits.Lens\n",
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||
"import Data.Data.Lens\n",
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"\n",
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||
"import Control.Applicative\n",
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"import Data.Char as C\n",
|
||
"import qualified Data.Map as M\n",
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||
"import qualified Data.Set as S\n",
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||
"import qualified Data.Text as T\n",
|
||
"import qualified Data.List as L"
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||
]
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},
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"</style><span class='get-type'>both :: forall (r :: * -> * -> *) (f :: * -> *) a b. (Bitraversable r, Applicative f) => (a -> f b) -> r a a -> f (r b b)</span>"
|
||
],
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|
||
"both :: forall (r :: * -> * -> *) (f :: * -> *) a b. (Bitraversable r, Applicative f) => (a -> f b) -> r a a -> f (r b b)"
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]
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"text/plain": [
|
||
"[\"Bubbles\",\"Buttercup\"]"
|
||
]
|
||
},
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"metadata": {},
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"output_type": "display_data"
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},
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{
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"data": {
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"text/plain": [
|
||
"(\"Bubbles!\",\"Buttercup!\")"
|
||
]
|
||
},
|
||
"metadata": {},
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||
"output_type": "display_data"
|
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},
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||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"(\"Blossom\",\"Blossom\")"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"(7,9)"
|
||
]
|
||
},
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||
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||
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|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"(10,20,30)"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
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||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[10,20,30]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"\"HERE'S JOHNNY\""
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"ename": "",
|
||
"evalue": "",
|
||
"output_type": "error",
|
||
"traceback": [
|
||
"<interactive>:1:43: error:\n • Couldn't match type ‘Int’ with ‘Char’ arising from a use of ‘each’\n • In the first argument of ‘(.~)’, namely ‘each’\n In the second argument of ‘(&)’, namely ‘each .~ (22 :: Int)’\n In the expression: (\"Houston we have a problem\" :: T.Text) & each .~ (22 :: Int)"
|
||
]
|
||
}
|
||
],
|
||
"source": [
|
||
"-- both is a traversal which focuses both sides of a tuple if it has the same type in each side\n",
|
||
"\n",
|
||
"-- Specialized to tuples\n",
|
||
"-- both :: Traversal (a, a) (b, b) a b\n",
|
||
"\n",
|
||
"-- General\n",
|
||
"-- both :: Bitraversable r => Traversal (r a a) (r b b) a b\n",
|
||
"\n",
|
||
":t both\n",
|
||
"\n",
|
||
"(\"Bubbles\", \"Buttercup\") ^.. both\n",
|
||
"\n",
|
||
"(\"Bubbles\", \"Buttercup\") & both %~ (++ \"!\")\n",
|
||
"\n",
|
||
"(\"Bubbles\", \"Buttercup\") & both .~ \"Blossom\"\n",
|
||
"\n",
|
||
"(\"Bubbles\", \"Buttercup\") & both %~ length\n",
|
||
"\n",
|
||
"(1, 2, 3) & each %~ (*10)\n",
|
||
"\n",
|
||
"[1, 2, 3] & each %~ (*10)\n",
|
||
"\n",
|
||
"(\"Here's Johnny\" :: T.Text) & each %~ C.toUpper\n",
|
||
"\n",
|
||
"(\"Houston we have a problem\" :: T.Text) & each .~ (22 :: Int)"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "code",
|
||
"execution_count": 13,
|
||
"metadata": {},
|
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|
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{
|
||
"data": {
|
||
"text/plain": [
|
||
"[10,20,30,4,5]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
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{
|
||
"data": {
|
||
"text/plain": [
|
||
"[1,2,3,40,50]"
|
||
]
|
||
},
|
||
"metadata": {},
|
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"output_type": "display_data"
|
||
},
|
||
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|
||
"data": {
|
||
"text/plain": [
|
||
"\"ONCE UPON A TIME - optics became mainstream\""
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
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{
|
||
"data": {
|
||
"text/plain": [
|
||
"[1,20,3,40,5]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"(\"short\",\"gnol yllaer\")"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
}
|
||
],
|
||
"source": [
|
||
"[1, 2, 3, 4, 5] & taking 3 traversed *~ 10\n",
|
||
"\n",
|
||
"[1, 2, 3, 4, 5] & dropping 3 traversed *~ 10\n",
|
||
"\n",
|
||
"-- focus characters until '-'\n",
|
||
"\"once upon a time - optics became mainstream\" & takingWhile (/= '-') traversed %~ toUpper\n",
|
||
"\n",
|
||
"-- filter can be used to filter focuses from a traversal\n",
|
||
"\n",
|
||
"-- Multiply all even numbers by 10\n",
|
||
"[1, 2, 3, 4, 5] & traversed . filtered even *~ 10\n",
|
||
"\n",
|
||
"-- Reverse only the long strings\n",
|
||
"(\"short\", \"really long\") & both . filtered ((> 5) . length) %~ reverse"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "markdown",
|
||
"metadata": {},
|
||
"source": [
|
||
"### Traversal Combinators"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "code",
|
||
"execution_count": 23,
|
||
"metadata": {},
|
||
"outputs": [
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{
|
||
"data": {
|
||
"text/html": [
|
||
"<style>/* Styles used for the Hoogle display in the pager */\n",
|
||
".hoogle-doc {\n",
|
||
"display: block;\n",
|
||
"padding-bottom: 1.3em;\n",
|
||
"padding-left: 0.4em;\n",
|
||
"}\n",
|
||
".hoogle-code {\n",
|
||
"display: block;\n",
|
||
"font-family: monospace;\n",
|
||
"white-space: pre;\n",
|
||
"}\n",
|
||
".hoogle-text {\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
".hoogle-name {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-head {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-sub {\n",
|
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"display: block;\n",
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"display: block;\n",
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".err-msg {\n",
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"color: red;\n",
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"font-weight: bold;\n",
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"}\n",
|
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".err-msg.in.collapse {\n",
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"padding-top: 0.7em;\n",
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"}\n",
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".highlight-code {\n",
|
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"white-space: pre;\n",
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"font-family: monospace;\n",
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".suggestion-warning { \n",
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"font-weight: bold;\n",
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"color: rgb(200, 130, 0);\n",
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".suggestion-error { \n",
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"font-weight: bold;\n",
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"color: red;\n",
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".suggestion-name {\n",
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"font-weight: bold;\n",
|
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"}\n",
|
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"</style><span class='get-type'>traversed :: forall (p :: * -> * -> *) (f1 :: * -> *) (f2 :: * -> *) a b. (Indexable Int p, Traversable f1, Applicative f2) => p a (f2 b) -> f1 a -> f2 (f1 b)</span>"
|
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|
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"text/plain": [
|
||
"traversed :: forall (p :: * -> * -> *) (f1 :: * -> *) (f2 :: * -> *) a b. (Indexable Int p, Traversable f1, Applicative f2) => p a (f2 b) -> f1 a -> f2 (f1 b)"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[10,20,30]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"(\"Batman\",\"Sup\")"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"fromList [(\"Gohan\",\"710\"),(\"Goku\",\"Over 9000\"),(\"Krillin\",\"5000\"),(\"Piccolo\",\"408\")]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"Node {rootLabel = \"sneL\", subForest = [Node {rootLabel = \"dloF\", subForest = []},Node {rootLabel = \"lasrevarT\", subForest = []}]}"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
}
|
||
],
|
||
"source": [
|
||
"-- Errors out\n",
|
||
"-- [1, 2, 3] & folded %~ (*10)\n",
|
||
"\n",
|
||
"-- Simplified\n",
|
||
"-- traversed :: Traversable f => Traversal (f a) (f b) a b\n",
|
||
"\n",
|
||
"-- A bit more complex\n",
|
||
"-- traversed :: Traversable f => IndexedTraversal Int (f a) (f b) a b\n",
|
||
"\n",
|
||
"-- Actual\n",
|
||
":t traversed\n",
|
||
"\n",
|
||
"[1, 2, 3] & traversed *~ 10\n",
|
||
"\n",
|
||
"-- Tuples are traversable over their last slot\n",
|
||
"(\"Batman\", \"Superman\") & traversed %~ take 3\n",
|
||
"\n",
|
||
"let powerLevels = M.fromList [ (\"Gohan\", 710), (\"Goku\", 9001), (\"Krillin\", 5000), (\"Piccolo\", 408) ]\n",
|
||
"\n",
|
||
"powerLevels & traversed %~ \\n -> if n > 9000 then \"Over 9000\" else show n\n",
|
||
"\n",
|
||
"import Data.Tree\n",
|
||
"\n",
|
||
"let opticsTree = Node \"Lens\" [Node \"Fold\" [], Node \"Traversal\" []]\n",
|
||
"\n",
|
||
"opticsTree & traversed %~ reverse"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "markdown",
|
||
"metadata": {},
|
||
"source": [
|
||
"### More Combinators"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "code",
|
||
"execution_count": 30,
|
||
"metadata": {},
|
||
"outputs": [
|
||
{
|
||
"data": {
|
||
"text/html": [
|
||
"<style>/* Styles used for the Hoogle display in the pager */\n",
|
||
".hoogle-doc {\n",
|
||
"display: block;\n",
|
||
"padding-bottom: 1.3em;\n",
|
||
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|
||
"}\n",
|
||
".hoogle-code {\n",
|
||
"display: block;\n",
|
||
"font-family: monospace;\n",
|
||
"white-space: pre;\n",
|
||
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|
||
".hoogle-text {\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
".hoogle-name {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
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|
||
".hoogle-head {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-sub {\n",
|
||
"display: block;\n",
|
||
"margin-left: 0.4em;\n",
|
||
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|
||
".hoogle-package {\n",
|
||
"font-weight: bold;\n",
|
||
"font-style: italic;\n",
|
||
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|
||
".hoogle-module {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-class {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".get-type {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
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|
||
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|
||
"white-space: pre-wrap;\n",
|
||
"}\n",
|
||
".show-type {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
"font-family: monospace;\n",
|
||
"margin-left: 1em;\n",
|
||
"}\n",
|
||
".mono {\n",
|
||
"font-family: monospace;\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
".err-msg {\n",
|
||
"color: red;\n",
|
||
"font-style: italic;\n",
|
||
"font-family: monospace;\n",
|
||
"white-space: pre;\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
"#unshowable {\n",
|
||
"color: red;\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".err-msg.in.collapse {\n",
|
||
"padding-top: 0.7em;\n",
|
||
"}\n",
|
||
".highlight-code {\n",
|
||
"white-space: pre;\n",
|
||
"font-family: monospace;\n",
|
||
"}\n",
|
||
".suggestion-warning { \n",
|
||
"font-weight: bold;\n",
|
||
"color: rgb(200, 130, 0);\n",
|
||
"}\n",
|
||
".suggestion-error { \n",
|
||
"font-weight: bold;\n",
|
||
"color: red;\n",
|
||
"}\n",
|
||
".suggestion-name {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
"</style><span class='get-type'>worded :: forall (p :: * -> * -> *) (f :: * -> *). (Indexable Int p, Applicative f) => p String (f String) -> String -> f String</span>"
|
||
],
|
||
"text/plain": [
|
||
"worded :: forall (p :: * -> * -> *) (f :: * -> *). (Indexable Int p, Applicative f) => p String (f String) -> String -> f String"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/html": [
|
||
"<style>/* Styles used for the Hoogle display in the pager */\n",
|
||
".hoogle-doc {\n",
|
||
"display: block;\n",
|
||
"padding-bottom: 1.3em;\n",
|
||
"padding-left: 0.4em;\n",
|
||
"}\n",
|
||
".hoogle-code {\n",
|
||
"display: block;\n",
|
||
"font-family: monospace;\n",
|
||
"white-space: pre;\n",
|
||
"}\n",
|
||
".hoogle-text {\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
".hoogle-name {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-head {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-sub {\n",
|
||
"display: block;\n",
|
||
"margin-left: 0.4em;\n",
|
||
"}\n",
|
||
".hoogle-package {\n",
|
||
"font-weight: bold;\n",
|
||
"font-style: italic;\n",
|
||
"}\n",
|
||
".hoogle-module {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-class {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".get-type {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
"font-family: monospace;\n",
|
||
"display: block;\n",
|
||
"white-space: pre-wrap;\n",
|
||
"}\n",
|
||
".show-type {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
"font-family: monospace;\n",
|
||
"margin-left: 1em;\n",
|
||
"}\n",
|
||
".mono {\n",
|
||
"font-family: monospace;\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
".err-msg {\n",
|
||
"color: red;\n",
|
||
"font-style: italic;\n",
|
||
"font-family: monospace;\n",
|
||
"white-space: pre;\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
"#unshowable {\n",
|
||
"color: red;\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".err-msg.in.collapse {\n",
|
||
"padding-top: 0.7em;\n",
|
||
"}\n",
|
||
".highlight-code {\n",
|
||
"white-space: pre;\n",
|
||
"font-family: monospace;\n",
|
||
"}\n",
|
||
".suggestion-warning { \n",
|
||
"font-weight: bold;\n",
|
||
"color: rgb(200, 130, 0);\n",
|
||
"}\n",
|
||
".suggestion-error { \n",
|
||
"font-weight: bold;\n",
|
||
"color: red;\n",
|
||
"}\n",
|
||
".suggestion-name {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
"</style><span class='get-type'>lined :: forall (p :: * -> * -> *) (f :: * -> *). (Indexable Int p, Applicative f) => p String (f String) -> String -> f String</span>"
|
||
],
|
||
"text/plain": [
|
||
"lined :: forall (p :: * -> * -> *) (f :: * -> *). (Indexable Int p, Applicative f) => p String (f String) -> String -> f String"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[\"I'll\",\"be\",\"back!\"]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[\"Run\",\"Forrest\",\"Run\"]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"\"*blue* *suede* *shoes*\""
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"\"Blue Suede Shoes\""
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"\"#blue\\n#suede\\n#shoes\""
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"\"blue suede shoes\""
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
}
|
||
],
|
||
"source": [
|
||
"-- worded :: Traversal' String String\n",
|
||
"-- lined :: Traversal' String String\n",
|
||
"\n",
|
||
":t worded\n",
|
||
":t lined\n",
|
||
"\n",
|
||
"\"I'll be back!\" ^.. worded\n",
|
||
"\n",
|
||
"\"Run\\nForrest\\nRun\" ^.. lined\n",
|
||
"\n",
|
||
"-- Surround each word with '*'s\n",
|
||
"\"blue suede shoes\" & worded %~ \\s -> \"*\" ++ s ++ \"*\"\n",
|
||
"\n",
|
||
"-- Capitalize each word\n",
|
||
"\"blue suede shoes\" & worded %~ \\(x:xs) -> C.toUpper x : xs\n",
|
||
"\n",
|
||
"-- Add a \"#\" to the start of each line:\n",
|
||
"\"blue\\nsuede\\nshoes\" & lined %~ ('#':)\n",
|
||
"\n",
|
||
"-- Mapping the identity function still has the\n",
|
||
"-- white-space collapsing side-effects of `unwords`\n",
|
||
"\"blue \\n suede \\n \\n shoes\" & worded %~ id"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "markdown",
|
||
"metadata": {},
|
||
"source": [
|
||
"### Traversing multiple paths at once"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "code",
|
||
"execution_count": 42,
|
||
"metadata": {},
|
||
"outputs": [
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[\"T-Rex\",\"Stegosaurus\"]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[1,2,3,4,5,6,7]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[\"T-Rex\",\"Ankylosaurus\",\"Stegosaurus\"]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"(\"COWABUNGA\",[\"LET'S\",\"ORDER\",\"PIZZA\"])"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"Left (-1,-2)"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"Right [-3,-4]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
}
|
||
],
|
||
"source": [
|
||
"-- beside :: Traversal s t a b -> Traversal s' t' a b -> Traversal (s, s') (t, t') a b\n",
|
||
"\n",
|
||
"-- beside :: Lens s t a b -> Lens s' t' a b -> Traversal (s, s') (t, t') a b\n",
|
||
"-- beside :: Fold s a -> Fold s' a -> Fold (s, s') a\n",
|
||
"\n",
|
||
"let dinos = (\"T-Rex\", (42, \"Stegosaurus\"))\n",
|
||
"\n",
|
||
"dinos ^.. beside id _2\n",
|
||
"\n",
|
||
"let numbers = ([(1, 2), (3, 4)], [5, 6, 7])\n",
|
||
"\n",
|
||
"numbers ^.. beside (traversed . both) traversed\n",
|
||
"\n",
|
||
"(\"T-Rex\", (\"Ankylosaurus\", \"Stegosaurus\")) ^.. beside id both\n",
|
||
"\n",
|
||
"-- both = beside id id\n",
|
||
"\n",
|
||
"-- We can modify all characters inside both halves of the tuple\n",
|
||
"(\"Cowabunga\", [\"let's\", \"order\", \"pizza\"])\n",
|
||
" -- Each half of the tuple has a different path to focus the characters\n",
|
||
" & beside traversed (traversed . traversed)\n",
|
||
" %~ toUpper\n",
|
||
" \n",
|
||
"-- beside both traversed :: Traversal' (Either (Int, Int) [Int]) Int\n",
|
||
"Left (1, 2) & beside both traversed %~ negate\n",
|
||
"\n",
|
||
"Right [3, 4] & beside both traversed %~ negate :: Either (Int, Int) [Int]"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "markdown",
|
||
"metadata": {},
|
||
"source": [
|
||
"### Focusing a specific traversal element"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "code",
|
||
"execution_count": 44,
|
||
"metadata": {},
|
||
"outputs": [
|
||
{
|
||
"data": {
|
||
"text/html": [
|
||
"<style>/* Styles used for the Hoogle display in the pager */\n",
|
||
".hoogle-doc {\n",
|
||
"display: block;\n",
|
||
"padding-bottom: 1.3em;\n",
|
||
"padding-left: 0.4em;\n",
|
||
"}\n",
|
||
".hoogle-code {\n",
|
||
"display: block;\n",
|
||
"font-family: monospace;\n",
|
||
"white-space: pre;\n",
|
||
"}\n",
|
||
".hoogle-text {\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
".hoogle-name {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-head {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-sub {\n",
|
||
"display: block;\n",
|
||
"margin-left: 0.4em;\n",
|
||
"}\n",
|
||
".hoogle-package {\n",
|
||
"font-weight: bold;\n",
|
||
"font-style: italic;\n",
|
||
"}\n",
|
||
".hoogle-module {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-class {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".get-type {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
"font-family: monospace;\n",
|
||
"display: block;\n",
|
||
"white-space: pre-wrap;\n",
|
||
"}\n",
|
||
".show-type {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
"font-family: monospace;\n",
|
||
"margin-left: 1em;\n",
|
||
"}\n",
|
||
".mono {\n",
|
||
"font-family: monospace;\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
".err-msg {\n",
|
||
"color: red;\n",
|
||
"font-style: italic;\n",
|
||
"font-family: monospace;\n",
|
||
"white-space: pre;\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
"#unshowable {\n",
|
||
"color: red;\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".err-msg.in.collapse {\n",
|
||
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"</style><span class='get-type'>element :: forall (p :: * -> * -> *) (t :: * -> *) (f :: * -> *) a. (Indexable Int p, Traversable t, Applicative f) => Int -> p a (f a) -> t a -> f (t a)</span>"
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"element :: forall (p :: * -> * -> *) (t :: * -> *) (f :: * -> *) a. (Indexable Int p, Traversable t, Applicative f) => Int -> p a (f a) -> t a -> f (t a)"
|
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"Just 2"
|
||
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|
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"[0,1,200,3,4]"
|
||
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||
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|
||
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|
||
}
|
||
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|
||
"source": [
|
||
"-- element :: Traversable f => Int -> Traversal' (f a) a\n",
|
||
"\n",
|
||
":t element\n",
|
||
"\n",
|
||
"[0, 1, 2, 3, 4] ^? element 2\n",
|
||
"\n",
|
||
"[0, 1, 2, 3, 4] & element 2 *~ 100\n",
|
||
"\n",
|
||
"-- elementOf :: Traversal' s a -> Int -> Traversal' s a\n",
|
||
"-- elementOf :: Fold s a -> Int -> Fold s a\n",
|
||
"\n",
|
||
"-- `element` is basically `elementOf traversed`\n",
|
||
"[0, 1, 2, 3, 4] ^? elementOf traversed 2\n",
|
||
"\n",
|
||
"-- We can get a specific element from a composition of traversals\n",
|
||
"[[0, 1, 2], [3, 4], [5, 6, 7, 8]] ^? elementOf (traversed . traversed) 6\n",
|
||
"\n",
|
||
"-- Modify the 6th integer from within nested lists:\n",
|
||
"[[0, 1, 2], [3, 4], [5, 6, 7, 8]]\n",
|
||
" & elementOf (traversed . traversed) 6 *~ 100"
|
||
]
|
||
},
|
||
{
|
||
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|
||
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|
||
"source": [
|
||
"### Composing Traversals"
|
||
]
|
||
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|
||
{
|
||
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|
||
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|
||
"metadata": {},
|
||
"outputs": [
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"\"Blue Suede Shoes\""
|
||
]
|
||
},
|
||
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||
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|
||
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|
||
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||
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||
"text/plain": [
|
||
"[\"short\",\"*really* *long*\"]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
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|
||
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||
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|
||
"data": {
|
||
"text/plain": [
|
||
"((\"Rich Ritchie\",100000),(\"Archie\",32),(\"Rich Reggie\",4350))"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
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|
||
}
|
||
],
|
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|
||
"-- Capitalize the first char of every word\n",
|
||
"\"blue suede shoes\" & worded . taking 1 traversed %~ toUpper\n",
|
||
"\n",
|
||
"-- Find all strings longer than 5 chars\n",
|
||
"-- then surround each word in that string with '*'\n",
|
||
"[\"short\", \"really long\"]\n",
|
||
" & traversed\n",
|
||
" . filtered ((> 5) . length)\n",
|
||
" . worded\n",
|
||
" %~ \\s -> \"*\" ++ s ++ \"*\"\n",
|
||
" \n",
|
||
"-- Add \"Rich \" to the names of people with more than $1000\n",
|
||
"((\"Ritchie\", 100000), (\"Archie\", 32), (\"Reggie\", 4350))\n",
|
||
" & each\n",
|
||
" . filtered ((> 1000) . snd)\n",
|
||
" . _1\n",
|
||
" %~ (\"Rich \" ++)"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "markdown",
|
||
"metadata": {},
|
||
"source": [
|
||
"### Exercises - Simple Traversals"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "code",
|
||
"execution_count": 67,
|
||
"metadata": {},
|
||
"outputs": [
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"(\"N/A\",\"N/A\")"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"(\"xxxxxxxx\",\"xxxx\")"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"(\"Mal\",[\"Kay\",\"Ina\",\"Jay\"])"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"(\"Malcolm\",[\"Kaylee\",\"River\",\"Jayne\"])"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[\"Die xxxxxxx Day\",\"Live xxx Let Die\",\"You xxxx Live Twice\"]"
|
||
]
|
||
},
|
||
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|
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"</style><span class='get-type'>traversed :: forall (p :: * -> * -> *) (f1 :: * -> *) (f2 :: * -> *) a b. (Indexable Int p, Traversable f1, Applicative f2) => p a (f2 b) -> f1 a -> f2 (f1 b)</span>"
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|
||
"((True,\"STRAWberries\"),(False,\"Blueberries\"),(True,\"BLACKberries\"))"
|
||
]
|
||
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|
||
"metadata": {},
|
||
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|
||
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|
||
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|
||
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|
||
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|
||
"(\"Strawberries\",\"Blueberries\",\"Blackberries\")"
|
||
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|
||
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|
||
"metadata": {},
|
||
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|
||
}
|
||
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|
||
"source": [
|
||
"-- 1.\n",
|
||
"\n",
|
||
"-- What type of optic do you get when you compose a traversal with a fold?\n",
|
||
"-- We get a fold\n",
|
||
"\n",
|
||
"-- Which of the optics we have learned can act as a traversal?\n",
|
||
"-- Lens or Traversal\n",
|
||
"\n",
|
||
"-- Which of the optics we have learned can act as a fold?\n",
|
||
"-- Lens, traversal and fold\n",
|
||
"\n",
|
||
"-- 2.\n",
|
||
"-- Fill in the blank to complete each expression:\n",
|
||
"\n",
|
||
"(\"Jurassic\", \"Park\") & each .~ \"N/A\"\n",
|
||
"\n",
|
||
"(\"Jurassic\", \"Park\") & both . traversed .~ 'x'\n",
|
||
"\n",
|
||
"(\"Malcolm\", [\"Kaylee\", \"Inara\", \"Jayne\"])\n",
|
||
" & beside id traversed %~ take 3\n",
|
||
"\n",
|
||
"(\"Malcolm\", [\"Kaylee\", \"Inara\", \"Jayne\"])\n",
|
||
" & _2 . element 1 .~ \"River\"\n",
|
||
"\n",
|
||
"[\"Die Another Day\", \"Live and Let Die\", \"You Only Live Twice\"]\n",
|
||
" & traversed . elementOf worded 1 . traversed .~ 'x'\n",
|
||
"\n",
|
||
":t each\n",
|
||
":t traversed\n",
|
||
"\n",
|
||
"((True, \"Strawberries\"), (False, \"Blueberries\"), (True, \"Blackberries\")) \n",
|
||
" & each . filtered fst . _2 . taking 5 traversed %~ C.toUpper\n",
|
||
" \n",
|
||
"((True, \"Strawberries\"), (False, \"Blueberries\"), (True, \"Blackberries\"))\n",
|
||
" & each %~ snd"
|
||
]
|
||
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|
||
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"### Traversal Actions"
|
||
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|
||
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|
||
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|
||
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|
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||
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|
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|
||
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|
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|
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||
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||
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||
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||
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|
||
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||
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|
||
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|
||
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|
||
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||
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|
||
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|
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||
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||
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||
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||
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||
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||
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||
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||
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||
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||
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|
||
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||
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||
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||
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||
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|
||
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||
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||
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||
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||
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||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
"</style><span class='get-type'>readFile :: FilePath -> IO String</span>"
|
||
],
|
||
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|
||
"readFile :: FilePath -> IO String"
|
||
]
|
||
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|
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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||
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|
||
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|
||
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|
||
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|
||
".hoogle-text {\n",
|
||
"display: block;\n",
|
||
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|
||
".hoogle-name {\n",
|
||
"color: green;\n",
|
||
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|
||
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|
||
".hoogle-head {\n",
|
||
"font-weight: bold;\n",
|
||
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|
||
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|
||
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|
||
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|
||
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|
||
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||
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|
||
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|
||
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|
||
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|
||
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|
||
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||
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|
||
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|
||
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|
||
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|
||
"color: green;\n",
|
||
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|
||
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|
||
"display: block;\n",
|
||
"white-space: pre-wrap;\n",
|
||
"}\n",
|
||
".show-type {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
"font-family: monospace;\n",
|
||
"margin-left: 1em;\n",
|
||
"}\n",
|
||
".mono {\n",
|
||
"font-family: monospace;\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
".err-msg {\n",
|
||
"color: red;\n",
|
||
"font-style: italic;\n",
|
||
"font-family: monospace;\n",
|
||
"white-space: pre;\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
"#unshowable {\n",
|
||
"color: red;\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
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|
||
"padding-top: 0.7em;\n",
|
||
"}\n",
|
||
".highlight-code {\n",
|
||
"white-space: pre;\n",
|
||
"font-family: monospace;\n",
|
||
"}\n",
|
||
".suggestion-warning { \n",
|
||
"font-weight: bold;\n",
|
||
"color: rgb(200, 130, 0);\n",
|
||
"}\n",
|
||
".suggestion-error { \n",
|
||
"font-weight: bold;\n",
|
||
"color: red;\n",
|
||
"}\n",
|
||
".suggestion-name {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
"</style><span class='get-type'>results :: IO [String]</span>"
|
||
],
|
||
"text/plain": [
|
||
"results :: IO [String]"
|
||
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|
||
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|
||
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|
||
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|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[(\"a\",100),(\"a\",1000)]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
}
|
||
],
|
||
"source": [
|
||
":t sequenceA\n",
|
||
"\n",
|
||
"\n",
|
||
"sequenceA [Just 1, Just 2, Just 3]\n",
|
||
"\n",
|
||
"sequenceA [Just 1, Nothing, Just 3]\n",
|
||
"\n",
|
||
"sequenceA $ Just (Left \"Whoops\")\n",
|
||
"\n",
|
||
"sequenceA ([pure 1, pure 2, pure 3] :: [IO Int]) >>= print\n",
|
||
"\n",
|
||
":t traverse\n",
|
||
"\n",
|
||
"import Text.Read (readMaybe)\n",
|
||
"\n",
|
||
":t readMaybe\n",
|
||
"\n",
|
||
"traverse readMaybe [\"1\", \"2\", \"3\"] :: Maybe [Int]\n",
|
||
"\n",
|
||
"traverse readMaybe [\"1\", \"snark\", \"3\"] :: Maybe [Int]\n",
|
||
"\n",
|
||
":t readFile\n",
|
||
"\n",
|
||
"let results = traverse readFile [\"file1.txt\", \"file2.txt\"]\n",
|
||
"\n",
|
||
":t results\n",
|
||
"\n",
|
||
"traverse (\\n -> [n * 10, n * 100]) (\"a\", 10)"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "markdown",
|
||
"metadata": {},
|
||
"source": [
|
||
"### Traverse on Traversals"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "code",
|
||
"execution_count": 81,
|
||
"metadata": {},
|
||
"outputs": [
|
||
{
|
||
"data": {
|
||
"text/html": [
|
||
"<style>/* Styles used for the Hoogle display in the pager */\n",
|
||
".hoogle-doc {\n",
|
||
"display: block;\n",
|
||
"padding-bottom: 1.3em;\n",
|
||
"padding-left: 0.4em;\n",
|
||
"}\n",
|
||
".hoogle-code {\n",
|
||
"display: block;\n",
|
||
"font-family: monospace;\n",
|
||
"white-space: pre;\n",
|
||
"}\n",
|
||
".hoogle-text {\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
".hoogle-name {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-head {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-sub {\n",
|
||
"display: block;\n",
|
||
"margin-left: 0.4em;\n",
|
||
"}\n",
|
||
".hoogle-package {\n",
|
||
"font-weight: bold;\n",
|
||
"font-style: italic;\n",
|
||
"}\n",
|
||
".hoogle-module {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-class {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".get-type {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
"font-family: monospace;\n",
|
||
"display: block;\n",
|
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||
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||
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|
||
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||
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||
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|
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||
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"source": [
|
||
"-- Specialized signature\n",
|
||
"-- traverseOf :: Traversal s t a b -> (a -> f b) -> s -> f t\n",
|
||
"\n",
|
||
"-- Real signature\n",
|
||
"-- traverseOf :: LensLike f s t a b -> (a -> f b) -> s -> f t\n",
|
||
"\n",
|
||
":t traverse\n",
|
||
":t traverseOf\n",
|
||
":t traverseOf traversed\n",
|
||
"\n",
|
||
"traverseOf both readMaybe (\"1\", \"2\") :: Maybe (Int, Int)\n",
|
||
"\n",
|
||
"traverseOf both readMaybe (\"not a number\", \"2\") :: Maybe (Int, Int)\n",
|
||
"\n",
|
||
"traverseOf both (\\c -> [toLower c, toUpper c]) ('a', 'b')\n",
|
||
"\n",
|
||
"traverseOf\n",
|
||
" (both . traversed)\n",
|
||
" (\\c -> [toLower c, toUpper c])\n",
|
||
" (\"ab\", \"cd\")"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "code",
|
||
"execution_count": 88,
|
||
"metadata": {},
|
||
"outputs": [
|
||
{
|
||
"data": {
|
||
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|
||
"Right [(\"Mike\",\"mike@tmnt.io\"),(\"Raph\",\"raph@tmnt.io\"),(\"Don\",\"don@tmnt.io\"),(\"Leo\",\"leo@tmnt.io\")]"
|
||
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|
||
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|
||
},
|
||
{
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"data": {
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|
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|
||
]
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||
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||
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||
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||
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|
||
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||
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|
||
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||
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||
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||
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||
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|
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||
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||
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|
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|
||
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||
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|
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|
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|
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|
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|
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|
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{
|
||
"data": {
|
||
"text/plain": [
|
||
"Just (\"Garfield\",\"Lasagna\")"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"Nothing"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"Just ([\"apples\"],[\"oranges\"])"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"Nothing"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
}
|
||
],
|
||
"source": [
|
||
"validateEmail :: String -> Either String String\n",
|
||
"validateEmail email | elem '@' email = Right email\n",
|
||
" | otherwise = Left (\"missing '@': \" <> email)\n",
|
||
" \n",
|
||
"traverseOf (traversed . _2) validateEmail\n",
|
||
" [ (\"Mike\", \"mike@tmnt.io\")\n",
|
||
" , (\"Raph\", \"raph@tmnt.io\")\n",
|
||
" , (\"Don\", \"don@tmnt.io\")\n",
|
||
" , (\"Leo\", \"leo@tmnt.io\")\n",
|
||
" ]\n",
|
||
" \n",
|
||
"traverseOf (traversed . _2) validateEmail\n",
|
||
" [ (\"Mike\", \"mike@tmnt.io\")\n",
|
||
" , (\"Raph\", \"raph.io\")\n",
|
||
" , (\"Don\", \"don@tmnt.io\")\n",
|
||
" , (\"Leo\", \"leo@tmnt.io\")\n",
|
||
" ]\n",
|
||
" \n",
|
||
"-- forOf :: Traversal s t a b -> s -> (a -> f b) -> f t\n",
|
||
":t forOf\n",
|
||
"\n",
|
||
"-- sequenceAOf :: Traversal s t (f a) a -> s -> f t\n",
|
||
":t sequenceAOf\n",
|
||
"\n",
|
||
"sequenceAOf _1 (Just \"Garfield\", \"Lasagna\")\n",
|
||
"\n",
|
||
"sequenceAOf _1 (Nothing, \"Lasagna\")\n",
|
||
"\n",
|
||
"sequenceAOf (both . traversed) ([Just \"apples\"], [Just \"oranges\"])\n",
|
||
"\n",
|
||
"sequenceAOf (both . traversed) ([Just \"apples\"], [Nothing])"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "code",
|
||
"execution_count": null,
|
||
"metadata": {},
|
||
"outputs": [],
|
||
"source": [
|
||
"-- traverseOf :: Traversal s t a b -> (a -> f b) -> s -> f t\n",
|
||
"-- (%%~) :: Traversal s t a b -> (a -> f b) -> s -> f t\n",
|
||
"\n",
|
||
"((\"1\", \"2\") & both %%~ readMaybe) :: Maybe (Int, Int)\n",
|
||
"\n",
|
||
"((\"not a number\", \"2\") & both %%~ readMaybe) :: Maybe (Int, Int)"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "markdown",
|
||
"metadata": {},
|
||
"source": [
|
||
"### Exercises - Traversal Actions"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "code",
|
||
"execution_count": 98,
|
||
"metadata": {},
|
||
"outputs": [
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"Nothing"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"ZipList {getZipList = [[1,3],[2,4]]}"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"ZipList {getZipList = [[('a',1),('b',3)],[('a',2),('b',4)]]}"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"(([1,2,3],(4,5)),5)"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
}
|
||
],
|
||
"source": [
|
||
"sequenceAOf _1 (Nothing, \"Rosebug\")\n",
|
||
"\n",
|
||
"-- sequenceAOf (traversed . _1) [(\"ab\", 1), (\"cd\", 2)]\n",
|
||
"\n",
|
||
"sequenceAOf traversed [ZipList [1, 2], ZipList [3, 4]]\n",
|
||
"\n",
|
||
"sequenceAOf (traversed . _2) [('a', ZipList [1, 2]), ('b', ZipList [3, 4])]\n",
|
||
"\n",
|
||
"import Control.Monad.State\n",
|
||
"let result = traverseOf (beside traversed both) (\\n -> modify (+n) >> get) ([1, 1, 1], (1, 1))\n",
|
||
"runState result 0"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "markdown",
|
||
"metadata": {},
|
||
"source": [
|
||
"### Custom Traversals"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "code",
|
||
"execution_count": 104,
|
||
"metadata": {},
|
||
"outputs": [
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[Deposit {_amount = 100},Withdrawal {_amount = 20},Withdrawal {_amount = 10}]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[100,20,10]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[10,30]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[Deposit {_amount = 100},Withdrawal {_amount = 20},Deposit {_amount = 300}]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
}
|
||
],
|
||
"source": [
|
||
"-- values :: Traversal [a] [b] a b\n",
|
||
"\n",
|
||
"-- values :: Applicative f => (a -> f b) -> [a] -> f [b]\n",
|
||
"\n",
|
||
"values :: Applicative f => (a -> f b) -> [a] -> f [b]\n",
|
||
"values _ [] = pure []\n",
|
||
"values handler (a : as) = liftA2 (:) (handler a) (values handler as)\n",
|
||
"\n",
|
||
"data Transaction =\n",
|
||
" Withdrawal { _amount :: Int }\n",
|
||
" | Deposit { _amount :: Int }\n",
|
||
" deriving Show\n",
|
||
" \n",
|
||
"makeLenses ''Transaction\n",
|
||
"\n",
|
||
"newtype BankAccount =\n",
|
||
" BankAccount\n",
|
||
" { _transactions :: [Transaction]\n",
|
||
" } deriving Show\n",
|
||
"makeLenses ''BankAccount\n",
|
||
"\n",
|
||
"let aliceAccount = BankAccount [Deposit 100, Withdrawal 20, Withdrawal 10]\n",
|
||
"\n",
|
||
"aliceAccount ^.. transactions . traversed\n",
|
||
"\n",
|
||
"aliceAccount ^.. transactions . traversed . amount\n",
|
||
"\n",
|
||
"-- deposits :: Traversal' [Transaction] Int\n",
|
||
"-- deposits :: Traversal [Transaction] [Transaction] Int Int\n",
|
||
"deposits :: Applicative f => (Int -> f Int) -> [Transaction] -> f [Transaction]\n",
|
||
"deposits _ [] = pure []\n",
|
||
"deposits handler (Withdrawal amt : rest) =\n",
|
||
" liftA2 (:) (pure (Withdrawal amt)) (deposits handler rest)\n",
|
||
"deposits handler (Deposit amt : rest) =\n",
|
||
" liftA2 (:) (Deposit <$> (handler amt)) (deposits handler rest)\n",
|
||
" \n",
|
||
"[Deposit 10, Withdrawal 20, Deposit 30] ^.. deposits\n",
|
||
"\n",
|
||
"[Deposit 10, Withdrawal 20, Deposit 30] & deposits *~ 10"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "markdown",
|
||
"metadata": {},
|
||
"source": [
|
||
"### Exercises - Custom Traversals"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "code",
|
||
"execution_count": 105,
|
||
"metadata": {},
|
||
"outputs": [],
|
||
"source": [
|
||
"amountT :: Traversal' Transaction Int\n",
|
||
"amountT handler (Deposit n) = Deposit <$> handler n\n",
|
||
"amountT handler (Withdrawal n) = Withdrawal <$> handler n\n",
|
||
"\n",
|
||
"myBoth :: Traversal (a, a) (b, b) a b\n",
|
||
"myBoth handler (a, a') = liftA2 (,) (handler a) (handler a')\n",
|
||
"\n",
|
||
"transactionDelta :: Traversal' Transaction Int\n",
|
||
"transactionDelta handler (Deposit n) = Deposit <$> handler n\n",
|
||
"transactionDelta handler (Withdrawal n) = Withdrawal . negate <$> handler (negate n)\n",
|
||
"\n",
|
||
"left :: Traversal (Either a b) (Either a' b) a a'\n",
|
||
"left f (Left a) = Left <$> f a\n",
|
||
"left _ (Right b) = pure (Right b)\n",
|
||
"\n",
|
||
"beside :: Traversal s t a b -> Traversal s' t' a b -> Traversal (s,s') (t,t') a b\n",
|
||
"beside left' right' handler (s, s') = liftA2 (,) (s & left' %%~ handler) (s' & right' %%~ handler)"
|
||
]
|
||
},
|
||
{
|
||
"cell_type": "code",
|
||
"execution_count": 113,
|
||
"metadata": {},
|
||
"outputs": [
|
||
{
|
||
"data": {
|
||
"text/html": [
|
||
"<style>/* Styles used for the Hoogle display in the pager */\n",
|
||
".hoogle-doc {\n",
|
||
"display: block;\n",
|
||
"padding-bottom: 1.3em;\n",
|
||
"padding-left: 0.4em;\n",
|
||
"}\n",
|
||
".hoogle-code {\n",
|
||
"display: block;\n",
|
||
"font-family: monospace;\n",
|
||
"white-space: pre;\n",
|
||
"}\n",
|
||
".hoogle-text {\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
".hoogle-name {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-head {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-sub {\n",
|
||
"display: block;\n",
|
||
"margin-left: 0.4em;\n",
|
||
"}\n",
|
||
".hoogle-package {\n",
|
||
"font-weight: bold;\n",
|
||
"font-style: italic;\n",
|
||
"}\n",
|
||
".hoogle-module {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".hoogle-class {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".get-type {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
"font-family: monospace;\n",
|
||
"display: block;\n",
|
||
"white-space: pre-wrap;\n",
|
||
"}\n",
|
||
".show-type {\n",
|
||
"color: green;\n",
|
||
"font-weight: bold;\n",
|
||
"font-family: monospace;\n",
|
||
"margin-left: 1em;\n",
|
||
"}\n",
|
||
".mono {\n",
|
||
"font-family: monospace;\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
".err-msg {\n",
|
||
"color: red;\n",
|
||
"font-style: italic;\n",
|
||
"font-family: monospace;\n",
|
||
"white-space: pre;\n",
|
||
"display: block;\n",
|
||
"}\n",
|
||
"#unshowable {\n",
|
||
"color: red;\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
".err-msg.in.collapse {\n",
|
||
"padding-top: 0.7em;\n",
|
||
"}\n",
|
||
".highlight-code {\n",
|
||
"white-space: pre;\n",
|
||
"font-family: monospace;\n",
|
||
"}\n",
|
||
".suggestion-warning { \n",
|
||
"font-weight: bold;\n",
|
||
"color: rgb(200, 130, 0);\n",
|
||
"}\n",
|
||
".suggestion-error { \n",
|
||
"font-weight: bold;\n",
|
||
"color: red;\n",
|
||
"}\n",
|
||
".suggestion-name {\n",
|
||
"font-weight: bold;\n",
|
||
"}\n",
|
||
"</style><span class='get-type'>partsOf :: forall (f :: * -> *) s t a. Functor f => Traversing (->) f s t a a -> LensLike f s t [a] [a]</span>"
|
||
],
|
||
"text/plain": [
|
||
"partsOf :: forall (f :: * -> *) s t a. Functor f => Traversing (->) f s t a a -> LensLike f s t [a] [a]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"\"abc\""
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[1,2,3]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[('c',1),('a',2),('t',3)]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[('l',1),('e',2),('o',3)]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[('x',1),('b',2),('c',3)]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[('c',1),('b',2),('a',3)]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[('f',1),('o',2),('o',3)]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"[('o',1),('f',2),('f',3)]"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
},
|
||
{
|
||
"data": {
|
||
"text/plain": [
|
||
"(\"a a desk how is\",\" like r\",\"aven writing\")"
|
||
]
|
||
},
|
||
"metadata": {},
|
||
"output_type": "display_data"
|
||
}
|
||
],
|
||
"source": [
|
||
"-- partsOf :: Traversal' s a -> Lens' s [a]\n",
|
||
":t partsOf\n",
|
||
"\n",
|
||
"[('a', 1), ('b', 2), ('c', 3)] ^. partsOf (traversed . _1)\n",
|
||
"[('a', 1), ('b', 2), ('c', 3)] ^. partsOf (traversed . _2)\n",
|
||
"\n",
|
||
"[('a', 1), ('b', 2), ('c', 3)]\n",
|
||
" & partsOf (traversed . _1) .~ ['c', 'a', 't']\n",
|
||
" \n",
|
||
"-- Any 'extra' list elements are simply ignored\n",
|
||
"[('a', 1), ('b', 2), ('c', 3)]\n",
|
||
" & partsOf (traversed . _1) .~ ['l', 'e', 'o', 'p', 'a', 'r', 'd']\n",
|
||
" \n",
|
||
"-- Providing too few elements will keep the originals\n",
|
||
"[('a', 1), ('b', 2), ('c', 3)]\n",
|
||
" & partsOf (traversed . _1) .~ ['x']\n",
|
||
" \n",
|
||
"[('a', 1), ('b', 2), ('c', 3)]\n",
|
||
" & partsOf (traversed . _1) %~ reverse\n",
|
||
" \n",
|
||
"[('o', 1), ('o', 2), ('f', 3)]\n",
|
||
" & partsOf (traversed . _1) %~ L.sort\n",
|
||
" \n",
|
||
"[('o', 1), ('o', 2), ('f', 3)]\n",
|
||
" & partsOf (traversed . _1) %~ tail\n",
|
||
"\n",
|
||
"(\"how is a raven \", \"like a \", \"writing desk\")\n",
|
||
" & partsOf (each . traversed) %~ unwords . L.sort . words"
|
||
]
|
||
}
|
||
],
|
||
"metadata": {
|
||
"kernelspec": {
|
||
"display_name": "Haskell",
|
||
"language": "haskell",
|
||
"name": "haskell"
|
||
},
|
||
"language_info": {
|
||
"codemirror_mode": "ihaskell",
|
||
"file_extension": ".hs",
|
||
"name": "haskell",
|
||
"pygments_lexer": "Haskell",
|
||
"version": "8.6.5"
|
||
}
|
||
},
|
||
"nbformat": 4,
|
||
"nbformat_minor": 2
|
||
}
|