<|>

An associative binary operation

This combinator implements choice. The parser p <|> q first applies p. If it succeeds, the value of p is returned. If p fails without consuming any input, parser q is tried. This combinator is defined equal to the mplus member of the MonadPlus class and the (<|>) member of Alternative. The parser is called predictive since q is only tried when parser p didn't consume any input (i.e.. the look ahead is 1). This non-backtracking behaviour allows for both an efficient implementation of the parser combinators and the generation of good error messages.

This combinator implements choice. The parser p <|> q first applies p. If it succeeds, the value of p is returned. If p fails without consuming any input, parser q is tried. This combinator is defined equal to the mplus member of the MonadPlus class and the (<|>) member of Alternative. The parser is called predictive since q is only tried when parser p didn't consume any input (i.e.. the look ahead is 1). This non-backtracking behaviour allows for both an efficient implementation of the parser combinators and the generation of good error messages.

Combines two images horizontally. This is an alias for horizJoin. infixr 5

Horizontally join two matrices. Visually:

( A ) <|> ( B ) = ( A | B )

Where both matrices A and B have the same number of rows. This condition is not checked.

An associative binary operation

Choose between two policies. If the first fails, run the second.

Provide alternative layouts of the same content. Invariant: both arguments must flatten to the same document.

First try the left parser, if that fails try the right. | If both fail, the error will come from the right one.

Nondeterministically choose between two computations.

(m <|> n) >>= k = (m >>= k) <|> (n >>= k)

(m <|> n) <|> o = m <|> (n <|> o)

empty <|> m = m

m <|> empty = m

Horizontally join two matrices. Visually:

( A ) <|> ( B ) = ( A | B )

This combinator implements choice. The parser p <|> q first applies p. If it succeeds, the value of p is returned. If p fails without consuming any input, parser q is tried. This combinator is defined equal to the mplus member of the MonadPlus class and the (<|>) member of Alternative. The parser is called predictive since q is only tried when parser p didn't consume any input (i.e.. the look ahead is 1). This non-backtracking behaviour allows for both an efficient implementation of the parser combinators and the generation of good error messages.

Same as the usual <|> except a Format is no Functor, let alone Alternative.

An associative binary operation on Tables.

Union of two APIs, first takes precedence in case of overlap. Example:

>>> :{
type MyApi = "books" :> Get '[JSON] [Book] -- GET /books
:<|> "books" :> ReqBody '[JSON] Book :> Post '[JSON] () -- POST /books
:}

Left-biased choice: if the left alternative succeeds, the right one is never tried.