Special treatment for lambda in Haskell source.

app/Main.hs

@@ -12,13 +12,14 @@ import           Data.Maybe             (fromMaybe)
 import qualified Data.Map  as Map
 import           Data.Text(Text)
 import qualified Data.Text as T
-              
+
 import qualified Token.Haskell          (tokenizer)
 import qualified Token.Skylighting
 import           Filter                 (renderBlock, renderInline)
 import           FindColumns            (findColumns)
 import           Alignment              (Processed)
-import System.IO
+import           Render.Latex           (latexPackages)
+import           System.IO
 
 data Options = Options {
     inlineSyntax :: Text
@@ -27,20 +28,42 @@ data Options = Options {
 main :: IO ()
 main = toJSONFilter runner
 
+-- https://www.logicmatters.net/latex-for-logicians/symbols/
+-- Just (MetaList [MetaBlocks [RawBlock (Format "tex") "\\usepackage{scalerel}"]])
+
 -- | Main body of Pandoc filter.
 --   Reads format option, metadata,
 --   and calls `walk` with `blockFormatter`.
 runner :: Maybe Format -> Pandoc -> IO Pandoc
-runner (fromMaybe (Format "text") -> format) input@(Pandoc (Meta meta) _) = do
-    hPutStrLn stderr (show opts)
-    return $ walk (blockFormatter opts format) input
+runner (fromMaybe (Format "text") -> format) input@(Pandoc (Meta meta) ast) = do
+    hPutStrLn stderr $ show opts
+    hPutStrLn stderr $ show $ Map.lookup "header-includes" meta
+    let top = if format == Format "latex"
+                 then Pandoc (Meta $ Map.alter modifyIncludes "header-includes" meta) ast
+                 else input
+    return $ walk (blockFormatter opts format) top
   where
+    -- | Check default syntax for inline code
     opts = case Map.lookup "inline-code" meta of
       Nothing                    -> Options "haskell" -- default
-      Just (MetaString       s)  -> Options s -- never needed?
-      Just (MetaInlines [Str s]) -> Options s
+      Just (MetaString       s ) -> Options  s -- never needed?
+      Just (MetaInlines [Str s]) -> Options  s
       Just  otherValue           -> error $ "inline-code: meta should be a string but is: " <> show otherValue
 
+-- | Add package dependencies to the meta "header-includes".
+modifyIncludes :: Maybe MetaValue -> Maybe MetaValue
+modifyIncludes = Just
+               . addTeXPackages latexPackages
+               . fromMaybe (MetaList [])
+  where
+    addTeXPackages :: [Text] -> MetaValue -> MetaValue
+    addTeXPackages = addTeXInclude
+                   . T.unlines
+                   . fmap (\name -> "\\usepackage{" <> name <> "}")
+    addTeXInclude :: Text -> MetaValue -> MetaValue
+    addTeXInclude rawTeX (MetaList ls) =
+      MetaList (MetaBlocks [RawBlock (Format "tex") rawTeX]:ls)
+
 -- | Select the desired format output then process it.
 --   Run tokenizer, analysis, and formatter.
 --

package.yaml

@@ -41,6 +41,7 @@ dependencies:
 - blaze-markup
 - HaTeX
 - pandoc-types
+- pandoc-lens
 - optics-core
 - optics-th
 - skylighting

pandoc-filter-indent.cabal

@@ -4,10 +4,10 @@ cabal-version: 1.12
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 54950c09cdef3ae347be5565c51f866814024d8f3304665a2873a0acdf7c41a2
+-- hash: 54d01b49a8b6f04c42145197372388471c0dc46ca4c7ca9623f6b08d2853cd25
 
 name:           pandoc-filter-indent
-version:        0.3.0.0
+version:        0.3.1.0
 synopsis:       Pandoc filter formatting Haskell code fragments using GHC lexer.
 description:    Formats marked code fragments, and allows `pandoc` to safely process rest of your literate program:
                 .
@@ -73,6 +73,7 @@ library
     , ghc-syntax-highlighter ==0.0.5.0
     , optics-core
     , optics-th
+    , pandoc-lens
     , pandoc-types
     , skylighting
     , text ==1.2.4.0
@@ -96,6 +97,7 @@ executable pandoc-filter-indent
     , optics-th
     , optparse-applicative
     , pandoc-filter-indent
+    , pandoc-lens
     , pandoc-types
     , skylighting
     , text ==1.2.4.0
@@ -119,6 +121,7 @@ test-suite pandoc-filter-indent-test
     , optics-core
     , optics-th
     , pandoc-filter-indent
+    , pandoc-lens
     , pandoc-types
     , quickcheck-text
     , skylighting

src/Render/Latex.hs

@@ -1,7 +1,7 @@
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE ViewPatterns      #-}
 -- | Render analyzed input into LaTeX table.
-module Render.Latex(latexFromColSpans, latexInline) where
+module Render.Latex(latexFromColSpans, latexInline, latexPackages) where
 
 import Data.Text(Text)
 import qualified Data.Text as T
@@ -100,6 +100,7 @@ formatToken (TOperator,">>"    ) = mathop "gg"
 formatToken (TOperator,">>>"   ) = mathop "ggg"
 formatToken (TOperator,"<<"    ) = mathop "ll"
 formatToken (TOperator,"<<<"   ) = mathop "lll"
+formatToken (TOther,   "λ"     ) = mathop "lambda" -- Haskell only?
 --formatToken (TOperator,"-<"    ) = mathop "prec"
 formatToken (TOther,   "-<"    ) = mathop "prec"
 formatToken (TOther,   ">-"    ) = mathop "succ"
@@ -114,7 +115,7 @@ formatToken (TOther,   "->"    ) = mathop "to"
 formatToken (TOther,   "=>"    ) = mathop "Rightarrow"
 formatToken (TOperator,"==>"   ) = mathop "implies"
 formatToken (TOperator,"|->"   ) = mathop "mapsto"
---formatToken (TOperator,"|=>"   ) = mathop "Mapsto" -- not in amssymb
+formatToken (TOperator,"|=>"   ) = mathop "Mapsto" -- requires stmaryrd
 formatToken (TOperator,"<>"    ) = mathop "diamond"
 formatToken (TOperator,"<$>"   ) = mathop "mathbin{\\ooalign{\\raise.29ex\\hbox{$\\scriptscriptstyle\\$$}\\cr\\hss$\\!\\lozenge$\\hss}}"
 formatToken (TOperator,"<*>"   ) = mathop "mathbin{\\ooalign{\\raise.37ex\\hbox{$\\scriptscriptstyle{*}$}\\cr\\hss$\\!\\lozenge$\\hss}}"
@@ -130,7 +131,7 @@ formatToken (TVar    , kwd     ) = "\\emph{"       <> protectText kwd  <> "}"
 formatToken (TNum    , kwd     ) = protectText kwd 
 formatToken (TKeyword, kwd     ) = "\\textbf{"     <> protectText kwd  <> "}"
 formatToken (TCons,    cons    ) = "\\textsc{"     <> protectText cons <> "}"
-formatToken (TOperator,"\\"    ) = mathop "lambda"
+--formatToken (TOperator,"\\"    ) = mathop "lambda"
 formatToken (TTikz mark,_      ) = mathop $ "tikzMark{" <> mark <> "}"
 --formatToken (TOther,   "`"     ) = mathop "textasciigrave"
 formatToken (TOther,   "`"     ) = protectText "`"
@@ -151,3 +152,6 @@ mathop code = "\\" <> code
 
 prologue :: Text
 prologue = T.concat ["\\usepackage{amssymb}"]
+
+latexPackages :: [Text]
+latexPackages  = ["stmaryrd"]

src/Token/Haskell.hs

@@ -37,6 +37,8 @@ tokenizer  = fmap ( joinEscapedOperators
 --   and text content.
 --   Only TikZ marks are recognized by looking up text content.
 recognizeToken :: (Token, Text) -> (MyTok, Text)
+recognizeToken (SymbolTok,  "\\") = -- special treatment for lambda
+  (TOther,               "λ"    )
 recognizeToken (CommentTok, tokText@(unTikzMark -> Just mark)) =
   (TTikz mark,           tokText)
 recognizeToken (tokType, tokText) =

stack.yaml

@@ -4,6 +4,7 @@ packages:
 extra-deps:
 - HaTeX-3.22.2.0@sha256:c491c38724d2c9beac25c5a11c1848e3e1e96bd08b3909bd9711870d3610a594,5407
 - less-arbitrary-0.1.3.0@sha256:6955d2b869c9eb196a16126cf602b21a0447e56ff05b197f61d985cb0535c988,2691
+- pandoc-lens-0.7.0@sha256:752120f2f39a108666fe08f7d4b4853779d1871e227301425a1dba6840f3bb62,1012
 # Dev only
 - ghc-check-0.3.0.1@sha256:651d9b2b75a5cbdb3c942117801bfa566079bcaf20360e4d0959f9e575c30b39,1070
 - haskell-lsp-0.22.0.0@sha256:636af17378c10db3c784df697f1a0a450c694f1cf4a88acd0ed58be90c5295ec,5315

test/example.md

@@ -38,6 +38,7 @@ Inline `<>` quote is here.
 ```{.haskell}
 test :: forall a. a -> b -> c -> d -> e
 test = do
+  (\x -> x)
   (>>=)
   x `elem` v
   (>=>)