A Refined Syntax of Standard ML

The specification of the syntax of Standard ML in the Definition of Standard ML (Revised) is spread over multiple chapters, which makes it hard to understand. Furthermore, the grammar allows many non-sensical forms that are of little use to programmers.

The grammar given below collects together all of the various forms into a single collected syntax. Furthermore, the grammar has been refined to make it more regular and to rule out some of the more ridiculous terms allowed by the Definition. Thus, the language defined by this grammar is a subset of that given in the Definition, but it should be more useful to the SML programmer.

The Collected Syntax of Standard ML

file

::=

progdec

::=

|

topdec

::=

|

|

sigdec

::=

signature sigbind ( and sigbind )^*

sigbind

::=

sigid = sigexp

sigexp

::=

sig specs end

|

sigid

|

sigexp wheretype

wheretype

::=

where type wheretypespec ( and wheretypespec )^*

wheretypespec

::=

tyvarseq tycon = ty

tyvarseq

::=

empty

|

tyvar

|

( tyvar ( , tyvar )^* )

spec

::=

val valdesc ( and valdesc )^*

|

type typdesc ( and typdesc )^*

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eqtype typdesc ( and typdesc )^*

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datatype datdesc ( and datdesc )^*

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datatype tycon = datatype longtycon

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exception exdesc ( and exdesc )^*

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structure strdesc ( and strdesc )^*

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include sigexp

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include sigid⁺

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spec sharingspec

sharingspec

::=

sharing type longtycon ( = longtycon )⁺

|

sharing longstrid ( = longstrid )⁺

specs

::=

( spec ;^? )^*

valdesc

::=

vid : ty

typdesc

::=

datdesc

::=

tyvarseq tycon = condesc ( | condesc )^*

condesc

::=

conid ( of ty )^?

exdesc

::=

conid ( of ty )^?

strdesc

::=

strid : sigexp

strdec

::=

|

structure strbind ( and strbind )^*

|

local strdecs in strdecs end

strdecs

::=

( strdec ; )^*

strbind

::=

strid sigconstraint^? = strexp

sigconstraint

::=

|

strexp

::=

struct strdecs end

|

longstrid

|

strexp sigconstraint

|

funid ( functorarg )

|

let strdecs in strexp end

functorarg

::=

|

fundec

::=

functor funbind ( and funbind )^*

funbind

::=

funid ( functorparam ) sigconstraint^? = strexp

functorparam

::=

|

dec

::=

val tyvarseq valbind ( and valbind )^*

|

val rec^? fnbind ( and fnbind )^*

|

fun tyvarseq fvalbind ( and fvalbind )^*

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type typbind ( and typbind )^*

|

datatype datbind ( and datbind )^* withtype^?

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datatype tycon = datatype longtycon

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abstype datbind withtype^? with decs end

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exception exbind ( and exbind )^*

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local decs in decs end

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open longstrid⁺

|

infix precedence^? valid⁺

|

infixr precedence^? valid⁺

|

nofix valid⁺

decs

::=

( dec ;^? )^*

valbind

::=

fnbind

::=

fvalbind

::=

fvalrule ( | fvalrule )^*

fvalrule

::=

op^? vid atpat⁺ ( : ty )^? = exp

|

( atpat vid atpat ) atpat⁺ ( : ty )^? = exp

|

( atpat vid atpat ) ( : ty )^? = exp

|

atpat vid atpat ( : ty )^? = exp

typbind

::=

tyvarseq tycon = ty

datbind

::=

tyvarseq tycon = conbind ( | conbind )^*

conbind

::=

op^? vid ( of ty )^?

withtype

::=

withtype typbind ( and typbind )^*

exbind

::=

|

vid = longvid

ty

::=

tuplety ( -> ty )^?

tuplety

::=

tyapp ( * tyapp )^*

tyapp

::=

tyarg⁺ longtycon

|

tyarg

::=

|

( ty ( , ty )^* )

atty

::=

tyvar

|

longtycon

|

( ty )

|

{ tyrow^? }

tyrow

::=

lab : ty ( , tyrow )^?

pat

::=

op^? vid ( : ty )^? as pat

|

infpat

::=

conpat ( vid conpat )^*

conpat

::=

op^? longvid atpat

|

atpat

::=

_

|

|

|

{ patrow^? }

|

( patseq^? )

|

[ patseq^? ]

patrow

::=

...

|

fieldpat ( , patrow )^?

fieldpat

::=

vid ( : ty )^? ( as pat )^?

|

lab = pat

patseq

::=

pat ( , pat )^*

exp

::=

|

case exp of match

|

while exp do exp

|

if exp then exp else exp

|

raise exp

|

fnexp

::=

handleexp

::=

orexp ( handle match )^*

orexp

::=

andexp ( orelse andexp )^*

andexp

::=

tyexp ( andalso tyexp )^*

tyexp

::=

infexp ( : ty )^*

infexp

::=

appexp ( vid appexp )^*

appexp

::=

atexp

::=

|

op^? longvid

|

# lab

|

{ exprow^? }

|

( expseq^? )

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[ expseq^? ]

|

( exp ( ; exp )⁺ )

|

let decs in exp ( ; exp )^* end

exprow

::=

fieldexp ( , fieldexp )^*

expseq

::=

exp ( , exp )^*

match

::=

mrule ( | mrule )^*

mrule

::=

exactlit

::=

chrlit

|

strlit

|

wordlit

|

intlit

lit

::=

|

reallit