progress

src/css/mk.css

@@ -2,13 +2,19 @@
    Author: Yann Esposito
 */
 /* Fonts */
+:root {
+    --lh: 16px;
+}
 body {
     font: 14px/1.4 monospace;
-    line-height: 16px;
+    line-height: var(--lh);
 }
 pre, pre code {
     line-height: 1em;
 }
+blockquote pre {
+    line-height: var(--lh);
+}
 /* Layout */
 body, h1, h2, h3, h4, h5, h6, pre, code, blockquote, ol, ul, ol ol, ul ul, ul ol, ol
 ul, li, p, section, header, footer, img {
@@ -20,8 +26,8 @@ ul, li, p, section, header, footer, img {
 }
 h1, h2, h3, h4, h5, h6, pre, code, blockquote, p, ul, ol, section, header,
 figure,table {
-    margin-top: 1em;
-    margin-bottom: 1em;
+    margin-top: var(--lh);
+    margin-bottom: var(--lh);
 }
 li {
     display: block;
@@ -122,7 +128,7 @@ hr {
     margin:0;
 }
 #table-of-contents {
-    margin-bottom: 1em;
+    margin-bottom: var(--lh);
 }
 #postamble:before, hr:after {
     text-align: center;
@@ -186,7 +192,7 @@ figure, .figure {
     margin-top: 0;
 }
 #postamble {
-    margin-top: 1em;
+    margin-top: var(--lh);
 }
 .timestamp-wrapper {
     font-size: 12px;
@@ -252,9 +258,9 @@ figure, .figure {
 @media (prefers-color-scheme: light) {
     :root {
         --bg: var(--b3);
-        --fg: var(--b00);
+        --fg: var(--b01);
         --bg2: var(--b2);
-        --fg2: var(--b1);
+        --fg2: var(--b00);
         --rfg: var(--b01);
         --rbg: var(--b2);
         --bdr: var(--b2);

src/posts/0010-Haskell-Now/fib_lazy.hs

@@ -1,4 +1,4 @@
 fib :: [Integer]
 fib = 1:1:zipWith (+) fib (tail fib)
 
-main = traverse_ print (take 20 (drop 200 fib))
+main = traverse print (take 20 (drop 200 fib))

src/posts/0010-Haskell-Now/fib_lazy_trace.hs

@@ -0,0 +1,11 @@
+import Debug.Trace
+
+-- like + but each time this is evaluated print a trace
+tracedPlus x y = trace ("> " ++ show x ++ " + " ++ show y) (x + y)
+
+fib :: [Integer]
+fib = 1:1:zipWith tracedPlus fib (tail fib)
+
+main = do
+  print (fib !! 10)
+  print (fib !! 12)

src/posts/0010-Haskell-Now/infinite_tree.hs

@@ -1,21 +1,21 @@
-import           Data.Tree (Tree,Forest(..))
-import qualified Data.Tree as Tree
+  import           Data.Tree (Tree,Forest(..))
+  import qualified Data.Tree as Tree
 
-data BinTree a = Empty
-               | Node a (BinTree a) (BinTree a)
-               deriving (Eq,Ord,Show)
+  data BinTree a = Empty
+                 | Node a (BinTree a) (BinTree a)
+                 deriving (Eq,Ord,Show)
 
--- | Function to transform our internal BinTree type to the
--- type of Tree declared in Data.Tree (from containers package)
--- so that the function Tree.drawForest can use
-binTreeToForestString :: (Show a) => BinTree a -> Forest String
-binTreeToForestString Empty = []
-binTreeToForestString (Node x left right) =
-  [Tree.Node (show x) ((binTreeToForestString left) ++ (binTreeToForestString right))]
+  -- | Function to transform our internal BinTree type to the
+  -- type of Tree declared in Data.Tree (from containers package)
+  -- so that the function Tree.drawForest can use
+  binTreeToForestString :: (Show a) => BinTree a -> Forest String
+  binTreeToForestString Empty = []
+  binTreeToForestString (Node x left right) =
+    [Tree.Node (show x) ((binTreeToForestString left) ++ (binTreeToForestString right))]
 
--- | Function that given a BinTree print a representation of it in the console
-prettyPrintTree :: (Show a) => BinTree a -> IO ()
-prettyPrintTree = putStrLn . Tree.drawForest . binTreeToForestString
+  -- | Function that given a BinTree print a representation of it in the console
+  prettyPrintTree :: (Show a) => BinTree a -> IO ()
+  prettyPrintTree = putStrLn . Tree.drawForest . binTreeToForestString
 
 nullTree = Node 0 nullTree nullTree
 

src/posts/0010-Haskell-Now/infinite_tree_2.hs

@@ -1,30 +1,30 @@
-import           Data.Tree (Tree,Forest(..))
-import qualified Data.Tree as Tree
+  import           Data.Tree (Tree,Forest(..))
+  import qualified Data.Tree as Tree
 
-data BinTree a = Empty
-               | Node a (BinTree a) (BinTree a)
-               deriving (Eq,Ord,Show)
+  data BinTree a = Empty
+                 | Node a (BinTree a) (BinTree a)
+                 deriving (Eq,Ord,Show)
 
--- | Function to transform our internal BinTree type to the
--- type of Tree declared in Data.Tree (from containers package)
--- so that the function Tree.drawForest can use
-binTreeToForestString :: (Show a) => BinTree a -> Forest String
-binTreeToForestString Empty = []
-binTreeToForestString (Node x left right) =
-  [Tree.Node (show x) ((binTreeToForestString left) ++ (binTreeToForestString right))]
+  -- | Function to transform our internal BinTree type to the
+  -- type of Tree declared in Data.Tree (from containers package)
+  -- so that the function Tree.drawForest can use
+  binTreeToForestString :: (Show a) => BinTree a -> Forest String
+  binTreeToForestString Empty = []
+  binTreeToForestString (Node x left right) =
+    [Tree.Node (show x) ((binTreeToForestString left) ++ (binTreeToForestString right))]
 
--- | Function that given a BinTree print a representation of it in the console
-prettyPrintTree :: (Show a) => BinTree a -> IO ()
-prettyPrintTree = putStrLn . Tree.drawForest . binTreeToForestString
+  -- | Function that given a BinTree print a representation of it in the console
+  prettyPrintTree :: (Show a) => BinTree a -> IO ()
+  prettyPrintTree = putStrLn . Tree.drawForest . binTreeToForestString
 
--- | take all element of a BinTree up to some depth
-treeTakeDepth _ Empty = Empty
-treeTakeDepth 0 _     = Empty
-treeTakeDepth n (Node x left right) = let
-          nl = treeTakeDepth (n-1) left
-          nr = treeTakeDepth (n-1) right
-          in
-              Node x nl nr
+  -- | take all element of a BinTree up to some depth
+  treeTakeDepth _ Empty = Empty
+  treeTakeDepth 0 _     = Empty
+  treeTakeDepth n (Node x left right) = let
+            nl = treeTakeDepth (n-1) left
+            nr = treeTakeDepth (n-1) right
+            in
+                Node x nl nr
 
 iTree = Node 0 (dec iTree) (inc iTree)
         where

src/posts/0010-Haskell-Now/io_sum_ask.hs

@@ -0,0 +1,19 @@
+import Data.Maybe
+import Text.Read (readMaybe)
+
+getListFromString :: String -> Maybe [Integer]
+getListFromString str = readMaybe $ "[" ++ str ++ "]"
+
+askUser :: IO [Integer]
+askUser = do
+  putStrLn "Enter a list of numbers (separated by comma):"
+  input <- getLine
+  let maybeList = getListFromString input
+  case maybeList of
+      Just l  -> return l
+      Nothing -> askUser
+
+main :: IO ()
+main = do
+  list <- askUser
+  print $ sum list

src/posts/0010-Haskell-Now/io_sum_safe.hs

@@ -1,18 +1,14 @@
 import Data.Maybe
-
-maybeRead :: Read a => String -> Maybe a
-maybeRead s = case reads s of
-                  [(x,"")]    -> Just x
-                  _           -> Nothing
+import Text.Read (readMaybe)
 
 getListFromString :: String -> Maybe [Integer]
-getListFromString str = maybeRead $ "[" ++ str ++ "]"
+getListFromString str = readMaybe $ "[" ++ str ++ "]"
 
 main :: IO ()
 main = do
   putStrLn "Enter a list of numbers (separated by comma):"
   input <- getLine
-  let maybeList = getListFromString input in
-      case maybeList of
-          Just l  -> print (sum l)
-          Nothing -> putStrLn "Bad format. Good Bye."
+  let maybeList = getListFromString input
+  case maybeList of
+    Just l  -> print (sum l)
+    Nothing -> putStrLn "Bad format. Good Bye."

src/posts/0010-Haskell-Now/shell.nix

@@ -1,25 +1,26 @@
-{ nixpkgs ? import (fetchTarball https://github.com/NixOS/nixpkgs/archive/19.09.tar.gz) {} }:
-let
-  inherit (nixpkgs) pkgs;
-  inherit (pkgs) haskellPackages;
+   { nixpkgs ? import (fetchTarball https://github.com/NixOS/nixpkgs/archive/19.09.tar.gz) {} }:
+   let
+     inherit (nixpkgs) pkgs;
+     inherit (pkgs) haskellPackages;
 
-  haskellDeps = ps: with ps; [
-    base
-    protolude
-  ];
+     haskellDeps = ps: with ps; [
+       base
+       protolude
+       containers
+     ];
 
-  ghc = haskellPackages.ghcWithPackages haskellDeps;
+     ghc = haskellPackages.ghcWithPackages haskellDeps;
 
-  nixPackages = [
-    ghc
-    pkgs.gdb
-    haskellPackages.cabal-install
-  ];
-in
-pkgs.stdenv.mkDerivation {
-  name = "env";
-  buildInputs = nixPackages;
-  shellHook = ''
-     export PS1="\n[hs:\033[1;32m\]\W\[\033[0m\]]> "
-  '';
-}
+     nixPackages = [
+       ghc
+       pkgs.gdb
+       haskellPackages.cabal-install
+     ];
+   in
+   pkgs.stdenv.mkDerivation {
+     name = "env";
+     buildInputs = nixPackages;
+     shellHook = ''
+        export PS1="\n[hs:\033[1;32m\]\W\[\033[0m\]]> "
+     '';
+   }