ast - Print Abstract Syntax Tree

--- title: ast categories: | debug version: 0.104.0 debug: | Print the abstract syntax tree (ast) for a pipeline. usage: | Print the abstract syntax tree (ast) for a pipeline. editLink: false contributors: false ---  # `ast` for [debug](/commands/categories/debug.md) <div class='command-title'>Print the abstract syntax tree (ast) for a pipeline.</div> ## Signature ```> ast {flags} (pipeline)``` ## Flags - `--json, -j`: Serialize to json - `--minify, -m`: Minify the nuon or json output - `--flatten, -f`: An easier to read version of the ast ## Parameters - `pipeline`: The pipeline to print the ast for. ## Input/output types: | input | output | | ------- | ------ | | nothing | table | ## Examples Print the ast of a string ```nu > ast 'hello' ``` Print the ast of a pipeline ```nu > ast 'ls | where name =~ README' ``` Print the ast of a pipeline with an error ```nu > ast 'for x in 1..10 { echo $x ' ``` Print the ast of a pipeline with an error, as json, in a nushell table ```nu > ast 'for x in 1..10 { echo $x ' --json | get block | from json ``` Print the ast of a pipeline with an error, as json, minified ```nu > ast 'for x in 1..10 { echo $x ' --json --minify ``` Print the ast of a string flattened ```nu > ast "'hello'" --flatten ╭───┬─────────┬──────────────┬───────────────╮ │ # │ content │ shape │ span │ ├───┼─────────┼──────────────┼───────────────┤ │ 0 │ 'hello' │ shape_string │ ╭───────┬───╮ │ │ │ │ │ │ start │ 0 │ │ │ │ │ │ │ end │ 7 │ │ │ │ │ │ ╰───────┴───╯ │ ╰───┴─────────┴──────────────┴───────────────╯ ``` Print the ast of a string flattened, as json, minified ```nu > ast "'hello'" --flatten --json --minify [{"content":"'hello'","shape":"shape_string","span":{"start":0,"end":7}}] ``` Print the ast of a pipeline flattened ```nu > ast 'ls | sort-by type name -i' --flatten ╭───┬─────────┬────────────────────┬────────────────╮ │ # │ content │ shape │ span │ ├───┼─────────┼────────────────────┼────────────────┤ │ 0 │ ls │ shape_external │ ╭───────┬───╮ │ │ │ │ │ │ start │ 0 │ │ │ │ │ │ │ end │ 2 │ │ │ │ │ │ ╰───────┴───╯ │ │ 1 │ | │ shape_pipe │ ╭───────┬───╮ │ │ │ │ │ │ start │ 3 │ │ │ │ │ │ │ end │ 4 │ │ │ │ │ │ ╰───────┴───╯ │ │ 2 │ sort-by │ shape_internalcall │ ╭───────┬────╮ │ │ │ │ │ │ start │ 5 │ │ │ │ │ │ │ end │ 12 │ │ │ │ │ │ ╰───────┴────╯ │ │ 3 │ type │ shape_string │ ╭───────┬────╮ │ │ │ │ │ │ start │ 13 │ │ │ │ │ │ │ end │ 17 │ │ │ │ │ │ ╰───────┴────╯ │ │ 4 │ name │ shape_string │ ╭───────┬────╮ │ │ │ │ │ │ start │ 18 │ │ │ │ │ │ │ end │ 22 │ │ │ │ │ │ ╰───────┴────╯ │ │ 5 │ -i │ shape_flag │ ╭───────┬────╮ │ │ │ │ │ │ start │ 23 │ │ │ │ │ │ │ end │ 25 │ │ │ │ │ │ ╰───────┴────╯ │ ╰───┴─────────┴────────────────────┴────────────────╯ ```

The `ast` command is a debugging tool that prints the abstract syntax tree (AST) of a given pipeline. It can output the AST in a table format, JSON format (optionally minified), or a flattened table format for easier readability. It supports pipelines with errors and can be used to inspect the structure of Nushell code.