`assert A == B` Assert

Play both sides silently and compare them event for event. It sounds nothing. If they differ, the line is an error that shows the first difference.

Two spellings that play the same events are the same music, and an assert is how a document says so.
Use it to pin a claim so it stays true while the document changes.

A slice, stated two ways.

bpm 90
 
Row ::= 1 2 3 4 5 6 7 '1
 
assert Row[:4] == 1 2 3 4
assert Row[::-1] == '1 7 6 5 4 3 2 1
Row

running…edit it and it re-runs as you type

c4 d4 e4 f4 g4 a4 b4 c5

bpm 90
 
assert c4 _2 == c4 +1
assert 1 3 5 == c4 i4 i3
assert {1, 3, 5} == 1Maj
1Maj _4

running…edit it and it re-runs as you type

c4 e4 g4

bpm 90
 
Fig ::= 1 2 3 4
 
assert Fig _2 == 1 _2 2 _2 3 _2 4 _2
assert Fig@~2 == 3 4 5 6
Fig Fig@~2

running…edit it and it re-runs as you type

c4 d4 e4 f4 e4 f4 g4 a4