Pickle a tree.

Unpickle a tree.

Doesn't create or consume anything, always succeeds.

The zero pickler.

Encodes nothing, always fails during unpickling. (Same as xpThrow "got xpZero").

No output when pickling, always generates an error with the specified message on unpickling.

Isomorphic pickler.

Returns everything (remaining), untouched.

xpId. (compat)

Return one element, untouched.

xpHead. (compat)

Specialised version of xpId. (compat)

Like xpText0, but fails on non-empty input.

Convert Text to/from String.

Transforms a pickler on lists to a pickler on single elements.

NB: Will error when the given pickler doesn't produce exactly one element.

Convert text to/from any type that implements Read and Show. Fails on unpickle if read fails.

Pickle to/from attribute.

Pickle attribute if Just is given, on unpickling return Just val when the attribute is found, Nothing otherwise.

Pickle an attribute with the specified name and value, fail if the same attribute is not present on unpickle.

xpAttribute (compat)

xpAttribute_ (compat)

Add an attribute with a fixed value.

When unpickling, tries to find the first element with the supplied name. Once such an element is found, it will commit to it and fail if any of the picklers don't match.

Pickle Element without a restriction on the name. The name as taken / returned as the first element of the triple.

Find element by name space, prefixes are ignored.

Pickler returns the first found Element untouched.

Unpickler wraps element in NodeElement.

A helper variant of xpElem for elements that contain attributes but no child tags.

A helper variant of xpElem for elements that contain child nodes but no attributes.

A helper variant of xpElem for elements that contain only character data.

Helper for Element values that don't contain anything.

When pickling, creates an empty element iff parameter is True.

When unpickling, checks whether element exists. Generates an error when the element is not empty.

Handle all elements with a given name. The unpickler will fail when any of the elements fails to unpickle.

Get the first non-element NodeContent from a node.

Converts Booleans to XML boolean values

• "true" and "1" are read as True
• "false" and "0" are read as False
• All other values generate an unpickle error

Will always generate "true" or "false" (not "0" or "1") when pickling.

Lift a pickler. Nothing is returned when the given pickler doesn't return a value (e.g. the element isn't found). Does not affect unpickling errors. Nothing is pickled to mempty.

A typical example is:

xpElemAttributes "score" $ xpOption $ xpAttribute "value" xpPrim

in which Just 5 is encoded as <score value="5"/> and Nothing as <score/>.

Optional conversion with default value.

Unlike xpWithDefault the default value is not encoded in the XML document, during unpickling the default value is inserted if the pickler doesn't return a value.

Attempt to use a pickler. Return a default value when the pickler doesn't return anything (doesn't touch on UnpickleError).

Unlike xpDefault, the default value is encoded in the XML document.

Standard pickler for maps

This pickler converts a map into a list of pairs of the form

<elt attr="key">value</elt>

Execute one of a list of picklers. The selector function is used during pickling, and the integer returned is taken as a 0-based index to select a pickler from pickler options. Unpickling is done by trying each list element in order until one returns a Result (the selector is not used).

This is typically used to handle each constructor of a data type. However, it can be used wherever multiple serialization strategies apply to a single type.

NB: This function will ignore all errors as long as one of the branches returns a result. Also, it will produce an error when all branches return NoResult. Use xpChoice for a saner version of this function.

Execute one of a list of picklers. The selector function is used during pickling, and the integer returned is taken as a 0-based index to select a pickler from pickler options. Unpickling is done by trying each list element in order until one returns a Result or an Error.

This is typically used to handle each constructor of a data type. However, it can be used wherever multiple serialization strategies apply to a single type.

This function is similar to xpAlt but it will stop unpickling on the first error. It will return NoResult iff all of the picklers return NoResult (or the list of picklers is empty).

Try the left pickler first and if that doesn't produce anything the right one. Wrapping the result in Left or Right, respectively.

Not to be confused with xpWrapEither.

Pickler that during pickling always uses the first pickler, and during unpickling tries the first, and on failure then tries the second.

When unpickling, tries to apply the pickler to all elements returning and consuming only matched elements.

Select a single element from the list and apply unpickler to it.

Returns no value when no element matches the predicate.

Fails when the unpickler doesn't return a value.

When pickling, this is a noop.

Tries to apply the pickler to all the remaining elements; fails if any of them don't match.

For unpickling, apply the given pickler to a subset of the elements determined by a given predicate.

Pickles like xpAll.

Apply unpickler to all elements with the given namespace.

Pickles like xpAll.

xpAll. (compat)

When unpickling, successively applies pickler to single elements until it doesn't return anything; returns all matched elements.

xpSeqWhile. (compat)

Like xpList, but only succeed during unpickling if at least a minimum number of elements are unpickled.

Combines 2 picklers.

xp2Tuple. (compat)

xp2Tuple.

Combines 3 picklers.

xp3Tuple. (compat)

Combines 4 picklers.

Combines 5 picklers.

You guessed it ... Combines 6 picklers.

Apply a bijection before pickling / after unpickling.

Ignore input/output and replace with constant values.

Like xpWrap, except it strips Right (and treats Left as a failure) during unpickling.

Not to be confused with xpEither.

Like xpWrap, but strips Just (and treats Nothing as a failure) during unpickling.

Like xpWrap, but strips Just (and treats Nothing as a failure) during unpickling, with specified error message for Nothing value.

Test predicate when unpickling. Fails with given error message when the predicate return false.

NB: The predicate will only be tested while unpickling. When pickling, this is a noop.

Instead of failing the pickler will return no result.

Unlift a pickler on Node values to a pickler on Element values. Nodes generated during pickling that are not Element values will be silently discarded.

Noop when pickling.

When unpickling, only give access to the first element.

When unpickling, don't consume the matched element(s), noop when pickling.

Run unpickler and consume and discard remaining elements.

When pickling, this is a noop.

Add a back trace level to the error report.

Override the last backtrace level in the error report.

Merge successive NodeContent values.

Try to extract the remainig elements, fail if there are none.