FEEL vs B-FEEL: every difference, engine-verified

B-FEEL is the business-friendly dialect of FEEL, defined in chapter 11 of the OMG DMN specification. Where standard FEEL propagates null through type errors, B-FEEL substitutes type defaults (0 for numbers, the empty string, false, the empty list) and coerces mixed-type arithmetic, so a single missing value does not collapse a whole decision to null.

Every row below was computed by evaluating the expression in both dialects with the same engine that powers the free online FEEL evaluator. Use its FEEL / B-FEEL toggle to reproduce any of them.

Conversion

Expression	FEEL	B-FEEL
number("abc")	null	0	Try it ↑
date("invalid")	null	1970-01-01	Try it ↑
duration("bad")	null	P0D	Try it ↑
time("25:00:00")	null	00:00:00Z	Try it ↑

Boolean & misc

Expression	FEEL	B-FEEL
not(null)	null	false	Try it ↑
true and null	null	false	Try it ↑
null < 1	null	false	Try it ↑

String

Expression	FEEL	B-FEEL
"total: " + 5	null	total: 5	Try it ↑
upper case(null)	null	(empty string)	Try it ↑
contains("abc", null)	null	false	Try it ↑
split(null, ",")	null	[]	Try it ↑

Numeric

Expression	FEEL	B-FEEL
1 + null	null	1	Try it ↑
1/0	null	0	Try it ↑
"5" * 2	null	10	Try it ↑
modulo(10, 0)	null	0	Try it ↑

List

Expression	FEEL	B-FEEL
sum([1, "2", 3])	null	4	Try it ↑
index of(null, 1)	null	[]	Try it ↑
sublist(null, 1)	null	[]	Try it ↑

Temporal

Expression	FEEL	B-FEEL
day of week(null)	null	(empty string)	Try it ↑
month of year(null)	null	(empty string)	Try it ↑

Range

Expression	FEEL	B-FEEL
before(null, 5)	null	false	Try it ↑
includes([1..10], null)	null	false	Try it ↑
overlaps(null, [1..5])	null	false	Try it ↑

Context

Expression	FEEL	B-FEEL
get entries(null)	null	[]	Try it ↑
{a: 1}.b + 1	null	1	Try it ↑

The function pages in the FEEL function reference document standard FEEL behavior.