Module parser 

Recursive-descent parser for the extended lambda calculus surface syntax.

The grammar is:

expr        ::= seq_expr
seq_expr    ::= right_expr (";" right_expr)*
right_expr  ::= lambda | let | fix | assign_expr
lambda      ::= "\" ident "." expr
let         ::= "let" ident "=" expr "in" expr
fix         ::= "fix" ident "." expr
assign_expr ::= app_expr (":=" right_expr)?
app_expr    ::= atom atom*
atom        ::= ident | "(" expr ")" | "ref" atom | "!" atom

Precedence, from loosest to tightest: ;, :=, application, prefix ref/!, atoms. Inside a lambda/let/fix body the parser admits a full expr (so ; is consumed), but the right-hand side of := admits only a right_expr, which keeps ; strictly above :=.

Functions

parse

Parse a full expression from a token slice.