Editing JOSS (section)

====Let====
{{code|Let}} was used to define user-defined functions.{{sfn|Gimble|1967|p=74-75}} Equivalent to BASIC's {{code|DEF FN}}.{{sfn|Gimble|1967|p=65}}

 Let t(x)=sin(x)/cos(x).
 Set j=t(1.1).
 Type j.

{{code|Let}} can also be used to set the value of a variable using a formula consisting of a constant:

 Let x=5.

From that point, it can be used identically to one created using {{code|Set}}. There is a subtle difference, however, when this X is referenced in code, the value will be calculated by evaluating the right-hand side. A {{code|Set}} is only evaluated once, so it is much faster.{{sfn|Gimble|1967|p=45}}

The system generally suggested using {{code|Let}} only in direct mode, saving them out for use in a program by inserting them at the top or bottom of the file. This avoided the {{code|Let}} being called multiple times during execution, as it would only be called once during the loading process.{{sfn|Gimble|1967|p=63}}