Last update: 2005-11-23 09:16:18 CET
Produced by gfdoc - a rudimentary GF document generator. (c) Aarne Ranta (aarne@cs.chalmers.se) 2002 under GNU GPL.
operations for precedence-dependent strings. five levels: p4 (constants), p3 (applications), p2 (products), p1 (sums), p0 (arrows)
resource Precedence = open Prelude in {
param
Prec = p4 | p3 | p2 | p1 | p0 ;
lintype
PrecTerm = Prec => Str ;
oper
pss : PrecTerm -> {s : PrecTerm} = \s -> {s = s} ;
change this if you want some other type of parentheses
mkParenth : Str -> Str = \str -> "(" ++ str ++ ")" ;
define ordering of precedences
nextPrec : Prec => Prec =
table {p0 => p1 ; p1 => p2 ; p2 => p3 ; _ => p4} ;
prevPrec : Prec => Prec =
table {p4 => p3 ; p3 => p2 ; p2 => p1 ; _ => p0} ;
mkPrec : Str -> Prec => Prec => Str = \str ->
table {
p4 => table { -- use the term of precedence p4...
_ => str} ; -- ...always without parentheses
p3 => table { -- use the term of precedence p3...
p4 => mkParenth str ; -- ...in parentheses if p4 is required...
_ => str} ; -- ...otherwise without parentheses
p2 => table {
p4 => mkParenth str ;
p3 => mkParenth str ;
_ => str} ;
p1 => table {
p1 => str ;
p0 => str ;
_ => mkParenth str} ;
p0 => table {
p0 => str ;
_ => mkParenth str}
} ;
make a string into a constant, of precedence p4
mkConst : Str -> PrecTerm =
\f ->
mkPrec f ! p4 ;
make a string into a 1/2/3 -place prefix operator, of precedence p3
mkFun1 : Str -> PrecTerm -> PrecTerm =
\f -> \x ->
table {k => mkPrec (f ++ x ! p4) ! p3 ! k} ;
mkFun2 : Str -> PrecTerm -> PrecTerm -> PrecTerm =
\f -> \x -> \y ->
table {k => mkPrec (f ++ x ! p4 ++ y ! p4) ! p3 ! k} ;
mkFun3 : Str -> PrecTerm -> PrecTerm -> PrecTerm -> PrecTerm =
\f -> \x -> \y -> \z ->
table {k => mkPrec (f ++ x ! p4 ++ y ! p4 ++ z ! p4) ! p3 ! k} ;
make a string into a non/left/right -associative infix operator, of precedence p
mkInfix : Str -> Prec -> PrecTerm -> PrecTerm -> PrecTerm =
\f -> \p -> \x -> \y ->
table {k => mkPrec (x ! (nextPrec ! p) ++ f ++ y ! (nextPrec ! p)) ! p ! k} ;
mkInfixL : Str -> Prec -> PrecTerm -> PrecTerm -> PrecTerm =
\f -> \p -> \x -> \y ->
table {k => mkPrec (x ! p ++ f ++ y ! (nextPrec ! p)) ! p ! k} ;
mkInfixR : Str -> Prec -> PrecTerm -> PrecTerm -> PrecTerm =
\f -> \p -> \x -> \y ->
table {k => mkPrec (x ! (nextPrec ! p) ++ f ++ y ! p) ! p ! k} ;
alternative: precedence as inherent feature
lintype TermWithPrec = {s : Str ; p : Prec} ;
oper
mkpPrec : Str -> Prec -> TermWithPrec =
\f -> \p ->
{s = f ; p = p} ;
usePrec : TermWithPrec -> Prec -> Str =
\x -> \p ->
mkPrec x.s ! x.p ! p ;
make a string into a constant, of precedence p4
mkpConst : Str -> TermWithPrec =
\f ->
mkpPrec f p4 ;
make a string into a 1/2/3 -place prefix operator, of precedence p3
mkpFun1 : Str -> TermWithPrec -> TermWithPrec =
\f -> \x ->
mkpPrec (f ++ usePrec x p4) p3 ;
mkpFun2 : Str -> TermWithPrec -> TermWithPrec -> TermWithPrec =
\f -> \x -> \y ->
mkpPrec (f ++ usePrec x p4 ++ usePrec y p4) p3 ;
mkpFun3 : Str -> TermWithPrec -> TermWithPrec -> TermWithPrec -> TermWithPrec =
\f -> \x -> \y -> \z ->
mkpPrec (f ++ usePrec x p4 ++ usePrec y p4 ++ usePrec z p4) p3 ;
make a string a into non/left/right -associative infix operator, of precedence p
mkpInfix : Str -> Prec -> TermWithPrec -> TermWithPrec -> TermWithPrec =
\f -> \p -> \x -> \y ->
mkpPrec (usePrec x (nextPrec ! p) ++ f ++ usePrec y (nextPrec ! p)) p ;
mkpInfixL : Str -> Prec -> TermWithPrec -> TermWithPrec -> TermWithPrec =
\f -> \p -> \x -> \y ->
mkpPrec (usePrec x p ++ f ++ usePrec y (nextPrec ! p)) p ;
mkpInfixR : Str -> Prec -> TermWithPrec -> TermWithPrec -> TermWithPrec =
\f -> \p -> \x -> \y ->
mkpPrec (usePrec x (nextPrec ! p) ++ f ++ usePrec y p) p ;
} ;