Grammar for the Core language

Expressions and matches

Declarations and Bindings

Note: In the fvalbind form above, if var has infix status then either op must be present, or var must be infixed. Thus, at the start of any clause, op var (atpat, atpat') may be written ( atpat var atpat'). The parentheses may be dropped if `:ty' or `=' follows immediately.

Type expressions

Patterns

Syntactic restrictions

• No pattern may bind the same var twice. No expression row, pattern row or type row may bind the same lab twice.
• No binding valbind, typbind, datbind or exbind may bind the same identifier twice; this applies also to value constructors within a datbind.
• In the left side tyvarseq tycon of any typbind or datbind, tyvarseq must not contain the same tyvar twice. Any tyvar occurring within the right side must occur in tyvarseq.
• For each value binding pat = exp within rec, exp must be of the form fn match, possibly enclosed in parentheses, and possibly constrained by one or more type expressions.
• No datbind or exbind may bind true, false, it, nil, ::, or ref.