Evaluate an expression

evaluate always evaluates an expression once and writes one formatted value.

What changes is the value supplied to that evaluation.

Mode	How to select it	Input to the expression
Closed	Do not provide --input or --source.	No incoming value.
Explicit value	Provide --input or -i.	One parsed CLI value.
Complete source	Provide --source or -s.	One array containing all source rows.

Evaluate a closed expression

A closed expression contains everything needed for its evaluation.

expressif evaluate "5 | add(3)"

The command writes only the result:

8

If the expression requires an incoming value, supply one with --input or use run for several values.

Evaluate one input value

expressif evaluate 'absolute | add(5)' --input -12

17

The value passed to --input uses Expressif literal syntax. Numbers, booleans, null, arrays, records, dates, temporal values, and text are supported. A simple unquoted scalar that is not another valid literal is treated as text when this is unambiguous.

Quote structured or punctuation-rich values for both Expressif and the host shell:

expressif evaluate 'count' --input '{1, 2, 3}'

--input can be supplied only once. To process several independent inputs, use run.

Evaluate a complete source

With --source, all rows are materialized into one array before evaluation.

expressif evaluate 'sum' --source numeric.csv --scalar

flowchart LR
    A[Source rows] --> B[One array]
    B --> C[evaluate once]
    C --> D[One result]

--source and --input cannot be combined. --scalar requires --source and a tabular source with exactly one column.

CSV files are read as tabular data. Other file extensions are interpreted as strict UTF-8 Expressif source expressions; the source expression must be closed and return an enumerable value or IDataReader.

See Run expressions over input data for CSV profiles and for evaluating once per source row.

Read the expression from a file

Supply the expression inline or with --file/-f, but not both.

expressif evaluate --file ./expressions/transform.expr

Expression files are strict UTF-8, may span several lines, and cannot be empty or contain only whitespace. Relative paths are resolved from the current working directory.

Read the result

Successful output contains no Result: prefix, which makes it suitable for pipelines and command substitution. A null result is rendered as null.

Failures are written to standard error. The exit status distinguishes invalid expressions or inputs from failures that occur during evaluation; see Automation and exit codes.