Add an operator to set the content of an element.

examples/interpolation.html

@@ -15,6 +15,9 @@
 <p>
     Hello, <a></a>.
 </p>
+<p>
+    Hello, <span><a>world</a></span>.
+</p>
 <p>
     Hello, <a></a>.
 </p>

examples/interpolation.slab

@@ -8,6 +8,7 @@ body
 p Hello, #('Charlie').
 p Hello, #(42).
 p Hello, #(a).
+p Hello, #(span | a | 'world').
 p Hello, #{a}.
 p Hello, #{a number #(1)}.
 p Hello, #{el x}.

src/Slab/Evaluate.hs

@@ -278,6 +278,15 @@ evalExpr env = \case
       (Int i, Int j) -> pure . Bool $ i == j
       (SingleQuoteString s, SingleQuoteString t) -> pure . Bool $ s == t
       _ -> throwE $ Error.EvaluateError $ "Unimplemented (equal): " <> T.pack (show (Equal a' b'))
+  Cons a b -> do
+    a' <- evalExpr env a
+    b' <- evalExpr env b
+    case (a', b') of
+      (Block bl, Block c) ->
+        pure . Block $ setContent [c] bl
+      (Block bl, SingleQuoteString s) ->
+        pure . Block $ setContent [BlockText Normal [Lit s]] bl
+      _ -> throwE $ Error.EvaluateError $ "Unimplemented (cons): " <> T.pack (show (Cons a' b'))
   Application a b -> do
     a' <- evalExpr env a
     b' <- evalExpr env b
@@ -286,7 +295,9 @@ evalExpr env = \case
     evalExpr capturedEnv code
   frag@(Frag _ _ _) -> do
     blocks <- evalFrag env ["frag"] "-" [] [] frag
-    pure . Block $ BlockList blocks
+    case blocks of
+      [bl] -> pure $ Block bl
+      _ -> pure . Block $ BlockList blocks
   Block b -> do
     b' <- eval env ["block"] b
     pure $ Block b'
@@ -322,6 +333,7 @@ evalInline env = \case
     code' <- evalExpr env code
     case code' of
       SingleQuoteString _ -> pure $ Place code'
+      Bool _ -> pure $ Place code'
       Int _ -> pure $ Place code'
       Block _ -> pure $ Place code'
       -- Variable x -> context x -- Should not happen after evalExpr

src/Slab/Parse.hs

@@ -235,6 +235,8 @@ operatorTable =
   , [InfixL (symbol "+" $> Add), InfixL (symbol "-" $> Sub)]
   , [InfixL (symbol ">" $> GreaterThan), InfixL (symbol "<" $> LesserThan)]
   , [InfixL (symbol "==" $> Equal)]
+  , -- I'd like to use : instead, but it is already used for objects...
+    [InfixR (symbol "|" $> Cons)]
   ]
 
 parserVariable' :: Parser Expr
@@ -682,7 +684,7 @@ parseLit :: InlineContext -> Parser Inline
 parseLit ctx = do
   s <- case ctx of
     NormalBlock -> M.takeWhile1P (Just "literal") (\c -> c /= '#' && c /= '\n')
-    InlineBlock -> M.takeWhile1P (Just "literal") (\c -> c /= '#' && c /= '\n' && c/= '}')
+    InlineBlock -> M.takeWhile1P (Just "literal") (\c -> c /= '#' && c /= '\n' && c /= '}')
   pure $ Lit s
 
 parsePlaceExpr :: Parser Inline
@@ -702,13 +704,13 @@ parsePlaceBlock = do
 -- | Equivalent to `parserBlock` but in an inline context.
 parseInlineBlock :: Parser Block
 parseInlineBlock = do
- header <- parserDiv <|> parserCall
- template <- parseInlines' InlineBlock
- -- Don't return anything of the template is empty. to avoid a newline when
- -- rendering.
- if null template
-   then pure $ header []
-   else pure $ header [BlockText Dot template]
+  header <- parserDiv <|> parserCall
+  template <- parseInlines' InlineBlock
+  -- Don't return anything of the template is empty. to avoid a newline when
+  -- rendering.
+  if null template
+    then pure $ header []
+    else pure $ header [BlockText Dot template]
 
 parseEscape :: Parser Inline
 parseEscape = do

src/Slab/Render.hs

@@ -156,6 +156,7 @@ renderInline = \case
   Syntax.Place code -> do
     case code of
       Syntax.SingleQuoteString s -> s
+      Syntax.Bool x -> T.pack $ show x
       Syntax.Int x -> T.pack $ show x
       Syntax.Block b -> TL.toStrict . renderHtml $ renderBlock b
       x -> error $ "renderInline: unhandled value: " <> show x

src/Slab/Syntax.hs

@@ -5,6 +5,7 @@ module Slab.Syntax
   , isDoctype
   , pasteBlocks
   , setAttrs
+  , setContent
   , CommentType (..)
   , Elem (..)
   , TrailingSym (..)
@@ -84,12 +85,18 @@ pasteBlocks a b = BlockList $ peel a <> peel b
   peel (BlockList xs) = xs
   peel x = [x]
 
--- | Set attrs on a the block, if it is a BlockElem.
+-- | Set attrs on a the first block, if it is a BlockElem.
 setAttrs :: [Attr] -> [Block] -> [Block]
 setAttrs attrs (BlockElem name mdot attrs' nodes : bs) =
   BlockElem name mdot (attrs' <> attrs) nodes : bs
 setAttrs _ bs = bs
 
+-- | Set the content on a block, if it is a BlockElem.
+setContent :: [Block] -> Block -> Block
+setContent nodes (BlockElem name mdot attrs _) =
+  BlockElem name mdot attrs nodes
+setContent _ b = b
+
 -- | A "passthrough" comment will be included in the generated HTML.
 data CommentType = NormalComment | PassthroughComment
   deriving (Show, Eq)
@@ -190,6 +197,9 @@ data Expr
   | GreaterThan Expr Expr
   | LesserThan Expr Expr
   | Equal Expr Expr
+  | -- Not really a cons for lists, but instead to add content to an element.
+    -- E.g. p : "Hello."
+    Cons Expr Expr
   | Block Block
   | -- Expr can be a fragment, so we can manipulate them with code later.
     -- We also capture the current environment.