The Lao Zi DSL

A purpose-built expression language for aggregation-over-data calculations. Compiles deterministically to SQL — validated at parse time, not runtime. No raw SQL exposure. Strict PEMDAS enforcement.

PEMDAS Operator Precedence

The recursive-descent parser explicitly encodes operator precedence. This means SUM(a) + SUM(b) * 100 always evaluates as SUM(a) + (SUM(b) * 100), not (SUM(a) + SUM(b)) * 100.

Precedence	Operators	Parser Method
1 (highest)	`( ) parentheses`	parsePrimary
2	`unary -`	parseUnary
3	`* / %`	parseMultiplicative
4 (lowest)	`+ -`	parseAdditive

Function Reference

Function	Description	Example
`SUM(column)`	Sum of values	`SUM(amount)`
`AVG(column)`	Arithmetic mean	`AVG(amount) OVER(90 days)`
`COUNT(*)`	Row count	`COUNT(*) WHERE(type = 'CREDIT')`
`COUNT(DISTINCT col)`	Distinct count	`COUNT(DISTINCT payee)`
`MIN(column)`	Minimum value	`MIN(amount)`
`MAX(column)`	Maximum value	`MAX(amount) OVER(last_year)`
`MEDIAN(column)`	50th percentile	`MEDIAN(amount)`
`STDEV(column)`	Standard deviation	`STDEV(amount) OVER(30 days)`

Named Periods

last_weekprior_weeklast_monthprior_monthlast_quarterprior_quarterlast_yearprior_yearYTDMTDWTDQTDQ1Q2Q3Q4last_N_dayslast_N_monthsprior_N_daysprior_N_months

Day filters: weekends, weekdays, monday–sunday (and abbreviations mon–sun).

Expression Examples

Income-to-Expense Ratio

Calculate the income-to-expense ratio as a percentage over the last 30 days, rounded to 2 decimal places.

ROUND(
  (SUM(amount) WHERE(type = 'income') OVER(30 days))
  /
  NULLIF(SUM(amount) WHERE(type = 'expense') OVER(30 days), 0)
  * 100,
  2
)

AggregationMathTemporalFilter

Credit Transaction Count

Count all credit transactions in the current year.

COUNT(*) WHERE(type = 'CREDIT') PERIOD(YTD)

AggregationFilterTemporal

Payee Concentration Index

Calculate the Gini coefficient for payment distribution across payees to detect concentration risk.

GINI(amount GROUP_BY(payee))

Statistical

Quarterly Revenue Change

Measure the percentage change in total revenue over the last 3 months.

CHANGE(amount, 3 months)

Temporal

High-Value Transaction Detection

Sum amounts of transactions exceeding $10,000 on weekends over the last 90 days.

SUM(amount) WHERE(amount > 10000 AND ON(weekends)) OVER(90 days)

AggregationFilterTemporal

Expense Volatility

Calculate the standard deviation of monthly expenses to measure spending volatility.

STDEV(amount) WHERE(type = 'expense') OVER(last_year)

AggregationFilterTemporal

Try It Live

Type a DSL expression below to see it parsed into an AST and compiled to SQL in real time. Click any example above to copy it, then paste it here.

DSL Expression

Press Ctrl+Enter to parse

Quick Examples