package ppxlib

Type of a pattern:

• 'a is the type of value matched by the pattern
• 'b is the continuation, for instance for a pattern that captures an int and a string, 'b will be int -> string -> _
• 'c is the result of the continuation.

Matches a value against a pattern. Raise a located error in case of failure.

Matches a value against a pattern and return a result.

Pattern that captures its input.

Same as __ but also captures the location.

Note: this should only be used for types that do not embed a location. For instance you can use it to capture a string constant:

estring __'

but using it to capture an expression would not yield the expected result:

pair (eint (int 42)) __'

In the latter case you should use the pexp_loc field of the captured expression instead.

Useful when some part of the AST is irrelevant. With __, the captured value is passed to the continuation, with drop it is ignored. In higher-level pattern matching, it is called wildcard pattern.

As-pattern. Passes the current node to the continuation.

Pitfall. In general, the continuation is called step by step by being applied partially to every next captured node in the pattern. That means that the node captured by as__ is passed to the continuation before checking if the pattern is matched.

alt stands for `alternatives'. It matches either the first pattern or the second one.

Same as alt, for the common case where the left-hand-side captures a value but not the right-hand-side.

Same as alt

Same as map