Values.to_nodes, Values.to_yaml, Values.to_yaml_file, Value.to_yaml, and Value.to_yaml_file now accept ~strict_keys (default: true). Exporting a map with duplicate keys raises Duplicate_key_error. The default is the opposite of the import-side default (false) because duplicate keys on export are almost always a bug and are not reliably supported across YAML implementations. Pass ~strict_keys:false to allow them through. Breaking change: existing code that serializes maps with duplicate keys will now raise Duplicate_key_error unless ~strict_keys:false is passed.Value.Build submodule — convenience constructors using zero_loc (#44, #45). Provides null, bool, int, int64, float, string, seq, and map for building value trees programmatically without repeating zero_loc. map takes (string * value) list; non-string keys require the Map constructor directly.\n (e.g. from a text field that already carried a line terminator) was incorrectly serialized as a Double_quoted scalar. It is now emitted as a > folded block (clip chomp), matching the output for the same string without the trailing newline (>-).3.14 is now printed as 3.14 instead of 3.1400000000000001.Node submodule — single-node interface for the lossless AST (#37, #38). Mirrors the Value module for the node type:
Node.t — forwarding type alias for node, exposing all four constructors (Node.Scalar_node, Node.Sequence_node, Node.Mapping_node, Node.Alias_node) alongside the top-level names.Node.has_comments : Node.t -> bool — returns true if the node or any descendant carries a comment (head, line, or foot).Node.pp / Node.show — aliases for pp_node / show_node.Nodes.has_comments : Nodes.t -> bool — returns true if any document in the parsed stream contains a comment. Both Node and Nodes expose has_comments on their own t.Value.t forwarding type (#36). Value.t is an alias for value that re-exports all constructors (Value.Null, Value.Bool, etc.) under the Value namespace.Value submodule — single-document interface for typed YAML values (#32). Most config files contain exactly one YAML document; the new Value module provides a cleaner API for this common case:
Value.of_yaml / of_yaml_exn: parse a string expecting one document.Value.of_yaml_file: read and parse a file expecting one document.Value.to_yaml / to_yaml_file: serialize a single value back to YAML.Value.equal: structural equality ignoring source locations.Value.compare: total order on values ignoring source locations.Value.pp / Value.show: pretty-printer and string renderer (aliases for the PPX-derived pp_value / show_value, which remain undeprecated for use by [@@deriving show] on types that embed value).Value.loc: extract the source location from any value constructor. The Values.one_of_yaml / one_of_yaml_exn / one_of_yaml_file functions and YAMLx.equal_value and YAMLx.value_loc are now deprecated in favor of their Value.* equivalents.Block scalar heuristics for Values.to_nodes / Values.to_yaml (#30). String values longer than 70 characters are now serialized using block scalar styles where appropriate:
| or |-), preserving newlines exactly.> or >-), with lines wrapped at approximately 70 characters.Plain or Double_quoted as before.reformat output format for the yamlx CLI (#30). yamlx -f reformat reads the input through the typed-value layer (dropping comments, anchors, and tags) and re-serializes using the block scalar heuristics above. This produces a normalized, human-readable YAML output from any conforming input.Node loc fields now exclude trailing whitespace and line terminators (#27):
end_pos is now right after the last content character, not past trailing spaces or consumed newlines.|, >): end_pos is now at the line terminator of the last content line, not at the start of the next token's line.--- document separator is now always emitted on its own line. Previously it was followed by a space and the document content on the same line for scalar and flow-collection documents, e.g. --- foo instead of ---\nfoo. (#25)head_comments of the value node. Previously they were silently discarded.foot_comments of the collection and printed at the correct indentation level. Previously they were attached to the last item's foot_comments and printed at column 0.| # note, > # note) are now captured and round-trip correctly. Previously the comment was silently dropped.---) are now attached as foot_comments of the preceding document rather than leaking into the head_comments of the following document's root node.foot_comments : string list field to Scalar_node and Alias_node (previously only collection nodes had this field).Initial release.
Cycle_error rather than looping forever.%YAML, %TAG).%YAML 1.1 directive).yes/no, on/off, y/n and their case variants.0755 in addition to 0o755.3:25:45 = 12345, 20:30.15 = 1230.15.<< mapping key merges the associated mapping(s) into the current mapping; explicit keys win over merged keys.Nodes module)node type preserves scalar style (plain / single-quoted / double-quoted / literal / folded), flow vs. block collection style, tags, anchors, and source positions (line, column, byte offset).Nodes.of_yaml / of_yaml_exn / of_yaml_file: parse YAML to a node list (one entry per document).Nodes.to_yaml: serialize back to YAML, round-tripping styles and comments.Nodes.to_plain_yaml / to_plain_yaml_exn: serialize to simplified YAML (aliases expanded, tags stripped, block collections only).Values module)value type: Null | Bool of bool | Int of int | Float of float | String of string | Seq of value list | Map of (value * value) list.Values.of_yaml / of_yaml_exn / of_yaml_file: parse and resolve in one step.Values.one_of_yaml / one_of_yaml_exn / one_of_yaml_file: parse a single-document stream and return the value directly (error on zero or multiple documents).Optional parameters on all resolution functions:
?schema: choose Yaml_1_2 (default) or Yaml_1_1.?strict_keys: raise Duplicate_key_error on duplicate mapping keys (default: keep the last occurrence silently).?plain: raise Simplicity_error if the input uses anchors, aliases, or explicit tags — useful when only simple, unambiguous YAML is acceptable.?strict_schema: error when a document's %YAML directive conflicts with the ?schema setting.?reject_ambiguous: with YAML 1.2, error on plain scalars that would resolve differently under YAML 1.1.Expansion_limit_exceeded before the node tree can grow unboundedly. Protects against YAML bombs.Depth_limit_exceeded rather than overflowing the stack.Error of error wrapper, making it straightforward to catch every YAMLx error in one place.error variants: Scan_error, Parse_error, Compose_error, Resolve_error, Schema_error, Duplicate_key_error, Simplicity_error, Cycle_error, Expansion_limit_exceeded, Depth_limit_exceeded, Printer_error.loc value with the start and end position (line, column, byte offset) of the offending input range.show_yaml_error: formats an error as a human-readable string. Accepts an optional ?format_loc parameter for custom location formatting (e.g. for LSP servers or structured logging).catch_errors: wraps a thunk, returning Ok value or Error message. Accepts an optional ?file argument to prefix messages with the file path.register_exception_printers: registers Printexc printers so YAMLx exceptions print legibly in uncaught-exception output.yamlx)Seven output formats selectable with -f FORMAT:
Format | Description |
|---|---|
| Re-emit YAML preserving styles and comments (default) |
| Simplified YAML: aliases expanded, tags stripped, block-only |
| Typed-value tree without source locations |
| Typed-value tree with source locations |
| AST without source locations or heights |
| Full AST with source locations, anchors, tags, and comments |
| yaml-test-suite event-tree notation (for debugging) |
Options:
--schema 1.1 / 1.2: choose the default YAML schema for the stream.--strict-schema: error when a document's %YAML directive contradicts --schema.--reject-ambiguous: with --schema 1.2, error on scalars that are ambiguous between YAML 1.1 and 1.2.--strict-keys: error on duplicate mapping keys (with -f value / value-loc).--plain: reject anchors, aliases, and tags in the input (with -f value / value-loc).--strict: with -f plain, error on tags rather than stripping them.--depth-limit N / --expansion-limit N: override the default safety limits.