ML Basis annotations control options that affect the elaboration of SML source files. Conceptually, a basis file is elaborated in a default annotation environment (just as it is elaborated in an empty basis). The declaration ann "ann" in basdec end merges the annotation ann with the "current" annotation environment for the elaboration of basdec. To allow for future expansion, "ann" is lexed as a single SML string constant. To conveniently specify multiple annotations, the following derived form is provided:

Here are the available annotations. In the explanation below, for annotations that take an argument, the first value listed is the default.

• allowFFI {false|true} 
  If true, allow _address, _export, _import, and _symbol expressions to appear in source files. See ForeignFunctionInterface.

• forceUsed 
  Force all identifiers in the basis denoted by the body of the ann to be considered used; use in conjunction with warnUnused true.

• nonexhaustiveExnMatch {default|ignore} 
  If ignore, suppress errors and warnings about nonexhaustive matches that arise solely from unmatched exceptions. If default, follow the behavior of nonexhaustiveMatch.

• nonexhaustiveMatch {warn|error|ignore} 
  If error or warn, report nonexhaustive matches. An error will abort a compile, while a warning will not.

• redundantMatch {warn|error|ignore} 
  If error or warn, report redundant matches. An error will abort a compile, while a warning will not.

• sequenceNonUnit {ignore|error|warn} 
  If error or warn, report when e1 is not of type unit in the sequence expression (e1; e2). This can be helpful in detecting curried applications that are mistakenly not hully applied. To silence spurious messages, you can use ignore e1.

• warnUnused {false|true} 
  Report unused identifiers.

Next Steps

• MLBasisAnnotationExamples