E0104: assignment_without_let

E0104 assignment_without_let — an assignment to a name that has no let.

A compile-time error of soma check, the checker of the Soma programming language (soma explain E0104).

The rule

In Soma a new variable is introduced with let; a plain totl = total + p to a name that has no let creates a new variable, so a typo silently leaves the real variable unchanged. soma check warns about it, and this binary reports the warning as W0014 (habit_warning), not as E0104; nothing is reported when the name is also a builtin, such as sum. Declare the variable with let before assigning it, or correct the name if you meant an existing one.

When you see it

soma check never prints E0104: the checker creates this diagnostic as a habit warning, and every habit warning is reported under the warning code W0014 (habit_warning), in edition 2026 and 2027 alike. An assignment to a name that is also a builtin (sum = 0) gets no diagnostic at all, because the check skips names it already knows.