Language.Haskell.Exts.Build

This module contains combinators to use when building Haskell source trees programmatically, as opposed to parsing them from a string. The contents here are quite experimental and will likely receive a lot of attention when the rest has stabilised.

Syntax building functions

name :: String -> Name

An identifier with the given string as its name. The string should be a valid Haskell identifier.

sym :: String -> Name

A symbol identifier. The string should be a valid Haskell symbol identifier.

var :: Name -> Exp

A local variable as expression.

op :: Name -> QOp

Use the given identifier as an operator.

qvar :: ModuleName -> Name -> Exp

A qualified variable as expression.

pvar :: Name -> Pat

A pattern variable.

app :: Exp -> Exp -> Exp

Application of expressions by juxtaposition.

infixApp :: Exp -> QOp -> Exp -> Exp

Apply an operator infix.

appFun :: Exp -> [Exp] -> Exp

Apply a function to a list of arguments.

pApp :: Name -> [Pat] -> Pat

A constructor pattern, with argument patterns.

tuple :: [Exp] -> Exp

A tuple expression.

pTuple :: [Pat] -> Pat

A tuple pattern.

varTuple :: [Name] -> Exp

A tuple expression consisting of variables only.

pvarTuple :: [Name] -> Pat

A tuple pattern consisting of variables only.

function :: String -> Exp

A function with a given name.

strE :: String -> Exp

A literal string expression.

charE :: Char -> Exp

A literal character expression.

intE :: Integer -> Exp

A literal integer expression.

strP :: String -> Pat

A literal string pattern.

charP :: Char -> Pat

A literal character pattern.

intP :: Integer -> Pat

A literal integer pattern.

doE :: [Stmt] -> Exp

A do block formed by the given statements. The last statement in the list should be a Qualifier expression.

lamE :: SrcLoc -> [Pat] -> Exp -> Exp

Lambda abstraction, given a list of argument patterns and an expression body.

letE :: [Decl] -> Exp -> Exp

A let ... in block.

caseE :: Exp -> [Alt] -> Exp

A case expression.

alt :: SrcLoc -> Pat -> Exp -> Alt

An unguarded alternative in a case expression.

altGW :: SrcLoc -> Pat -> [Stmt] -> Exp -> Binds -> Alt

An alternative with a single guard in a case expression.

listE :: [Exp] -> Exp

A list expression.

eList :: Exp

The empty list expression.

peList :: Pat

The empty list pattern.

paren :: Exp -> Exp

Put parentheses around an expression.

pParen :: Pat -> Pat

Put parentheses around a pattern.

qualStmt :: Exp -> Stmt

A qualifier expression statement.

genStmt :: SrcLoc -> Pat -> Exp -> Stmt

A generator statement: pat <- exp

letStmt :: [Decl] -> Stmt

A let binding group as a statement.

binds :: [Decl] -> Binds

Hoist a set of declarations to a binding group.

noBinds :: Maybe Binds

An empty binding group.

wildcard :: Pat

The wildcard pattern: _

genNames :: String -> Int -> [Name]

Generate k names by appending numbers 1 through k to a given string.

More advanced building

sfun :: SrcLoc -> Name -> [Name] -> Rhs -> Maybe Binds -> Decl

A function with a single clause

simpleFun :: SrcLoc -> Name -> Name -> Exp -> Decl

A function with a single clause, a single argument, no guards and no where declarations

patBind :: SrcLoc -> Pat -> Exp -> Decl

A pattern bind where the pattern is a variable, and where there are no guards and no 'where' clause.

patBindWhere :: SrcLoc -> Pat -> Exp -> [Decl] -> Decl

A pattern bind where the pattern is a variable, and where there are no guards, but with a 'where' clause.

nameBind :: SrcLoc -> Name -> Exp -> Decl

Bind an identifier to an expression.

metaFunction :: String -> [Exp] -> Exp

Apply function of a given name to a list of arguments.

metaConPat :: String -> [Pat] -> Pat

Apply a constructor of a given name to a list of pattern arguments, forming a constructor pattern.