Typst writer: improved handling of primes.

+ Use `'` instead of e.g. `prime`.
+ Don't put a space before primes.

Closes #239.

src/Text/TeXMath/Writers/Typst.hs

@@ -37,10 +37,19 @@ import Data.Maybe (fromMaybe)
 -- | Transforms an expression tree to equivalent Typst
 writeTypst :: DisplayType -> [Exp] -> Text
 writeTypst dt exprs =
-  T.unwords $ map writeExp $ everywhere (mkT $ S.handleDownup dt) exprs
+  writeExps $ everywhere (mkT $ S.handleDownup dt) exprs
 
 writeExps :: [Exp] -> Text
-writeExps = T.intercalate " " . map writeExp
+writeExps = go . map writeExp
+ where
+   go (a : b : es)
+    | T.take 1 b == "'" -- avoid space before a prime #239
+     = a <> go (b:es)
+   go (a : as)
+     = a <> if null as
+               then mempty
+               else " " <> go as
+   go [] = mempty
 
 inParens :: Text -> Text
 inParens s = "(" <> s <> ")"
@@ -101,6 +110,10 @@ writeExp (ENumber s) = s
 writeExp (ESymbol _t s)
   | T.all isAscii s = esc s  -- use '+' not 'plus'
   | s == "\x2212" = "-" -- use '-' not 'minus'
+  | s == "\8242" = "'" -- use ' for prime, see #239
+  | s == "\8243" = "''"
+  | s == "\8244" = "'''"
+  | s == "\8279" = "''''"
   | otherwise = fromMaybe (esc s) $ M.lookup s typstSymbolMap
 writeExp (EIdentifier s) =
   if T.length s == 1

test/regression/239.test

@@ -0,0 +1,4 @@
+<<< tex
+f'_n
+>>> typst
+f'_n

test/writer/typst/07.test

@@ -20,4 +20,4 @@
 , EIdentifier "a"
 ]
 >>> typst
-u prime.double + p (x) u prime + q (x) u = f (x) , quad x > a
+u'' + p (x) u' + q (x) u = f (x) , quad x > a

test/writer/typst/primes1.test

@@ -37,4 +37,4 @@
 , ESuper (ESymbol Accent "'") (ESymbol Accent "'")
 ]
 >>> typst
-x^2 + 2^2 + x^prime + x^(') + x^("''") + x prime + x^(')^(') + x^(')^2 + x^(' + ') + x^(')^(') + x^('^(')) + '^(') + '^(')
+x^2 + 2^2 + x^(') + x^(') + x^("''") + x' + x^(')^(') + x^(')^2 + x^(' +') + x^(')^(') + x^('^(')) +'^(') +'^(')

test/writer/typst/primes2.test

@@ -27,4 +27,4 @@
 , ESuper (EIdentifier "H") (ESymbol Accent "\8279")
 ]
 >>> typst
-H^(\") H^(') H^(\*) H^(`) H^ª H^degree H^(²) H^(³) H^acute H^(¹) H^º H^quote.l.single H^quote.r.single H^quote.low.single H^quote.high.single H^quote.l.double H^quote.r.double H^quote.low.double H^quote.high.double H^prime H^prime.double H^prime.triple H^prime.rev H^prime.double.rev H^prime.triple.rev H^prime.quad
+H^(\") H^(') H^(\*) H^(`) H^ª H^degree H^(²) H^(³) H^acute H^(¹) H^º H^quote.l.single H^quote.r.single H^quote.low.single H^quote.high.single H^quote.l.double H^quote.r.double H^quote.low.double H^quote.high.double H^(') H^('') H^(''') H^prime.rev H^prime.double.rev H^prime.triple.rev H^('''')