Stability | experimental |
---|---|
Maintainer | gershomb@gmail.com |
Simple DSL for lightweight (untyped) programmatic generation of Javascript.
A number of examples are available in the source of Language.Javascript.JMacro.Prelude.
Functions to generate generic RPC wrappers (using json serialization) are available in Language.Javascript.JMacro.Rpc.
usage:
renderJs [$jmacro|fun id x -> x|]
The above produces the id function at the top level.
renderJs [$jmacro|var id = \x -> x|]
So does the above here. However, as id is brought into scope by the keyword var, you do not get a variable named id in the generated javascript, but a variable with an arbitrary unique identifier.
renderJs [$jmacro|var !id = \x -> x|]
The above, by using the bang special form in a var declaration, produces a variable that really is named id.
renderJs [$jmacro|function id(x) {return x;}|]
The above is also id.
renderJs [$jmacro|function !id(x) {return x;}|]
As is the above (with the correct name).
renderJs [$jmacro|fun id x {return x;}|]
As is the above.
renderJs [$jmacroE|foo(x,y)|]
The above is an expression representing the application of foo to x and y.
renderJs [$jmacroE|foo x y|]]
As is the above.
renderJs [$jmacroE|foo (x,y)|]
While the above is an error. (i.e. standard javascript function application cannot seperate the leading parenthesis of the argument from the function being applied)
\x -> [$jmacroE|foo `(x)`|]
The above is a haskell expression that provides a function that takes an x, and yields an expression representing the application of foo to the value of x as transformed to a Javascript expression.
[$jmacroE|\x ->`(foo x)`|]
Meanwhile, the above lambda is in Javascript, and brings the variable into scope both in javascript and in the enclosed antiquotes. The expression is a Javascript function that takes an x, and yields an expression produced by the application of the Haskell function foo as applied to the identifier x (which is of type JExpr -- i.e. a Javascript expression).
Other than that, the language is essentially Javascript (1.5). Note however that one must use semicolons in a principled fashion -- i.e. to end statements consistently. Otherwise, the parser will mistake the whitespace for a whitespace application, and odd things will occur. A further gotcha exists in regex literals, whicch cannot begin with a space. x 5 4
parses as ((x 5) 4). However, x 5 4
will parse as x(5 , 4). Such are the perils of operators used as delimeters in the presence of whitespace application.
Additional features in jmacro (documented on the wiki) include an infix application operator, and an enhanced destructuring bind.
Additional datatypes can be marshalled to Javascript by proper instance declarations for the ToJExpr class.
An experimental typechecker is available in the Language.Javascript.JMacro.Typed module.
- jmacro :: QuasiQuoter
- jmacroE :: QuasiQuoter
- parseJM :: String -> Either ParseError JStat
- data JStat
- = DeclStat Ident (Maybe JLocalType)
- | ReturnStat JExpr
- | IfStat JExpr JStat JStat
- | WhileStat JExpr JStat
- | ForInStat Bool Ident JExpr JStat
- | SwitchStat JExpr [(JExpr, JStat)] JStat
- | TryStat JStat Ident JStat JStat
- | BlockStat [JStat]
- | ApplStat JExpr [JExpr]
- | PPostStat Bool String JExpr
- | AssignStat JExpr JExpr
- | UnsatBlock (IdentSupply JStat)
- | AntiStat String
- | ForeignStat Ident JLocalType
- | BreakStat
- data JExpr
- data JVal
- newtype Ident = StrI String
- newtype IdentSupply a = IS {
- runIdentSupply :: State [Ident] a
- class JMacro a where
- data MultiComp
- class Compos t where
- compos :: (forall a. a -> m a) -> (forall a b. m (a -> b) -> m a -> m b) -> (t -> m t) -> t -> m t
- composOp :: Compos t => (t -> t) -> t -> t
- composOpM :: (Compos t, Monad m) => (t -> m t) -> t -> m t
- composOpM_ :: (Compos t, Monad m) => (t -> m ()) -> t -> m ()
- composOpFold :: Compos t => b -> (b -> b -> b) -> (t -> b) -> t -> b
- withHygiene :: JMacro a => (a -> a) -> a -> a
- scopify :: JStat -> JStat
- renderJs :: (JsToDoc a, JMacro a) => a -> Doc
- renderPrefixJs :: (JsToDoc a, JMacro a) => String -> a -> Doc
- class JsToDoc a where
- class ToJExpr a where
- toJExpr :: a -> JExpr
- toJExprFromList :: [a] -> JExpr
- jsv :: String -> JExpr
- jLam :: ToSat a => a -> JExpr
- jVar :: ToSat a => a -> JStat
- jVarTy :: ToSat a => a -> Maybe JLocalType -> JStat
- jFor :: (ToJExpr a, ToStat b) => JStat -> a -> JStat -> b -> JStat
- jForIn :: ToSat a => JExpr -> (JExpr -> a) -> JStat
- jForEachIn :: ToSat a => JExpr -> (JExpr -> a) -> JStat
- jTryCatchFinally :: ToSat a => JStat -> a -> JStat -> JStat
- expr2stat :: JExpr -> JStat
- class ToStat a where
- nullStat :: JStat
- jhEmpty :: Map String JExpr
- jhSingle :: ToJExpr a => String -> a -> Map String JExpr
- jhAdd :: ToJExpr a => String -> a -> Map String JExpr -> Map String JExpr
- jhFromList :: [(String, JExpr)] -> JVal
- jsSaturate :: JMacro a => Maybe String -> a -> a
- jtFromList :: JType -> [(String, JType)] -> JType
- module Language.Javascript.JMacro.Prelude
- module Language.Javascript.JMacro.Types
Documentation
QuasiQuoter for a block of JMacro statements.
QuasiQuoter for a JMacro expression.
ADT
Statements
Expressions
Values
Identifiers
newtype IdentSupply a Source
IS | |
|
Functor IdentSupply | |
Typeable1 IdentSupply | |
Eq a => Eq (IdentSupply a) | |
Data a => Data (IdentSupply a) | |
Ord a => Ord (IdentSupply a) | |
Show a => Show (IdentSupply a) |
Generic traversal (via compos)
Utility class to coerce the ADT into a regular structure.
Union type to allow regular traversal by compos.
Compos and ops for generic traversal as defined over the JMacro ADT.
composOpFold :: Compos t => b -> (b -> b -> b) -> (t -> b) -> t -> bSource
Hygienic transformation
withHygiene :: JMacro a => (a -> a) -> a -> aSource
Apply a transformation to a fully saturated syntax tree, taking care to return any free variables back to their free state following the transformation. As the transformation preserves free variables, it is hygienic. Cannot be used nested.
scopify :: JStat -> JStatSource
Takes a fully saturated expression and transforms it to use unique variables that respect scope.
Display/Output
renderJs :: (JsToDoc a, JMacro a) => a -> DocSource
Render a syntax tree as a pretty-printable document (simply showing the resultant doc produces a nice, well formatted String).
renderPrefixJs :: (JsToDoc a, JMacro a) => String -> a -> DocSource
Render a syntax tree as a pretty-printable document, using a given prefix to all generated names. Use this with distinct prefixes to ensure distinct generated names between independent calls to render(Prefix)Js.
Ad-hoc data marshalling
Things that can be marshalled into javascript values. Instantiate for any necessary data structures.
ToJExpr Bool | |
ToJExpr Char | |
ToJExpr Double | |
ToJExpr Int | |
ToJExpr Integer | |
ToJExpr () | |
ToJExpr JSValue | |
ToJExpr JVal | |
ToJExpr JExpr | |
ToJExpr a => ToJExpr [a] | |
(ToJExpr a, ToJExpr b) => ToJExpr (a, b) | |
ToJExpr a => ToJExpr (Map String a) | |
(ToJExpr a, ToJExpr b, ToJExpr c) => ToJExpr (a, b, c) | |
(ToJExpr a, ToJExpr b, ToJExpr c, ToJExpr d) => ToJExpr (a, b, c, d) | |
(ToJExpr a, ToJExpr b, ToJExpr c, ToJExpr d, ToJExpr e) => ToJExpr (a, b, c, d, e) | |
(ToJExpr a, ToJExpr b, ToJExpr c, ToJExpr d, ToJExpr e, ToJExpr f) => ToJExpr (a, b, c, d, e, f) |
Literals
Occasionally helpful combinators
jLam :: ToSat a => a -> JExprSource
Create a new anonymous function. The result is an expression.
Usage:
jLam $ x y -> {JExpr involving x and y}
jVar :: ToSat a => a -> JStatSource
Introduce a new variable into scope for the duration
of the enclosed expression. The result is a block statement.
Usage:
jVar $ x y -> {JExpr involving x and y}
jVarTy :: ToSat a => a -> Maybe JLocalType -> JStatSource
Introduce a new variable with optional type into scope for the duration
of the enclosed expression. The result is a block statement.
Usage:
jVar $ x y -> {JExpr involving x and y}
jForIn :: ToSat a => JExpr -> (JExpr -> a) -> JStatSource
Create a for in statement.
Usage:
jForIn {expression} $ x -> {block involving x}
jForEachIn :: ToSat a => JExpr -> (JExpr -> a) -> JStatSource
As with jForIn but creating a "for each in" statement.
jTryCatchFinally :: ToSat a => JStat -> a -> JStat -> JStatSource
Hash combinators
jhFromList :: [(String, JExpr)] -> JValSource
Utility
jsSaturate :: JMacro a => Maybe String -> a -> aSource
Given an optional prefix, fills in all free variable names with a supply of names generated by the prefix.