Let statement
A let statement declares new local and global single assignment variables and binds a value to them. The syntax is the same as that of the var statement, except that the keyword var is replaced by the keyword let. Let variables are not l-values and can thus not be passed to var parameters nor can their address be taken. They cannot be assigned new values.
For let variables the same pragmas are available as for ordinary variables.
As let statements are immutable after creation they need to define a value when they are declared. The only exception to this is if the {.importc.} pragma (or any of the other importX pragmas) is applied, in this case the value is expected to come from native code, typically a C/C++ const.