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types.c
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/* MIRANDA TYPECHECKER */
/**************************************************************************
* Copyright (C) Research Software Limited 1985-90. All rights reserved. *
* The Miranda system is distributed as free software under the terms in *
* the file "COPYING" which is included in the distribution. *
* *
* Revised to C11 standard and made 64bit compatible, January 2020 *
*------------------------------------------------------------------------*/
#include "data.h"
#include "lex.h"
#include "big.h"
word R=NIL; /* direct-and-indirect dependency graph */
word TABSTRS=NIL; /* list of abstype declarations */
word ND; /* undefined names used in script */
word SBND; /* names specified but not defined (handled separately) */
word FBS; /* list of bindings caused by parameterised %include's */
word ATNAMES; /* global var set by abstr_check */
word NT=NIL; /* undefined typenames used in script */
word TYPERRS;
word bnf_t=0;
word current_id=0,lastloc=0,lineptr=0; /* used to locate type errors */
word showchain=NIL; /* links together all occurrences of special forms (show)
encountered during typecheck */
extern word rfl;
#include <setjmp.h>
jmp_buf env1; /* for longjmp - see man (3) setjmp */
static void abstr_check(word);
static void abstr_mcheck(word);
static void addsubst(word,word);
static word ap_subst(word,word);
static void checkfbs(void);
static int clear_SUBST(void);
static void comp_deps(word);
static word conforms(word,word,word,word);
static word cyclic_abstr(word);
static word etype(word,word,word);
static word fix_type(word);
static void fixshows(void);
static void genbnft(void);
static void infer_type(word);
static word linst(word,word);
static void locate_inc(void);
static void mcheckfbs(void);
static word meta_tcheck(word);
static int non_generic(word);
static int occurs(word,word);
static void out_formal(FILE*,word);
static void out_formal1(FILE*,word);
static void out_type1(word);
static void out_type2(word);
static void out_typel(word);
static void printelement(word);
static void redtfr(word);
static word rembvars(word,word);
static word remove1(word,word*);
static word rep_t(word,word);
static void sterilise(word);
static word subst(word);
static word subsu1(word,word,word);
static word tail(word);
static void txchange(word,word);
static void type_error(char*,char*,word,word);
static void type_error1(word);
static void type_error2(word);
static void type_error3(word);
static void type_error4(word);
static void type_error5(word);
static void type_error6(word,word,word);
static void type_error7(word,word);
static void type_error8(word,word);
static word ult(word);
static int unify(word,word);
static int unify1(word,word);
void checktypes() /* outcome indicated by setting of flags SYNERR, TYPERRS, ND */
{ word s;
extern word freeids,SYNERR,fnts;
ATNAMES=TYPERRS=0;
NT=R=SBND=ND=NIL; /* NT=R= added 4/6/88 */
if(setjmp(env1)==1)goto L;
if(rfl!=NIL)readoption();
for(s=reverse(fil_defs(hd[files]));s!=NIL;s=tl[s])
comp_deps(hd[s]); /* for each identifier in current script, compute
dependencies to form R */
R=tclos(sortrel(R));
if(FBS!=NIL)mcheckfbs();
abstr_mcheck(TABSTRS);
L:if(TYPERRS)
{ /* badly formed types, so give up */
TABSTRS=NT=R=NIL;
printf("typecheck cannot proceed - compilation abandoned\n");
SYNERR=1;
return; }
if(freeids!=NIL)redtfr(freeids);
/* printgraph("dependency analysis:",R); /* for debugging */
genshfns();
if(fnts!=NIL)genbnft();
R=msc(R);
/* printgraph("strong components:",R); /* for debugging */
s=tsort(R);
/* printlist("topological sort:",s); /* for debugging */
NT=R=NIL; /* must be invariant across the call */
while(s!=NIL)infer_type(hd[s]),s=tl[s];
checkfbs();
while(TABSTRS!=NIL)
abstr_check(hd[TABSTRS]),TABSTRS=tl[TABSTRS];
if(SBND!=NIL)
printlist("SPECIFIED BUT NOT DEFINED: ",alfasort(SBND)),SBND=NIL;
fixshows();
lastloc=0;
return;
}
/* NOTES
let element ::= id | list(id)
let graph1 ::= list(cons(id,list(id)))
let graph2 ::= list(cons(element,list(id)))
we define:
comp_deps(id)->builds R::graph1, direct dependencies
R=tclos(sortrel(R))::graph1, direct and indirect dependencies
msc(R)->collects maximal strong components in R, now R::graph2
tsort(graph2)->list(element), topologically sorted
infer_type(element)->fills in the id_type field(s) of element
*/
/* R occupies quadratic worst-case space - does anyone know a better way? */
void comp_deps(n) /* adds to R an entry of the form cons(n,RHS) where n is an
identifier and RHS is a list of all the identifiers in the
current script upon which n directly depends */
/* it also meta-typechecks type specifications, and puts them in reduced
form, as it goes */
word n;
{ word rhs=NIL,r;
/* printf("comp_deps(%s)\n",get_id(n)); /* DEBUG */
if(id_type(n)==type_t)
{ if(t_class(n)==algebraic_t)
{ r=t_info(n);
while(r!=NIL) /* meta type check constructors */
{ current_id=hd[r];
id_type(hd[r])=redtvars(meta_tcheck(id_type(hd[r])));
r=tl[r]; }
}
else if(t_class(n)==synonym_t)
current_id=n,t_info(n)=meta_tcheck(t_info(n));
else if(t_class(n)==abstract_t)
if(t_info(n)==undef_t)
printf("error: script contains no binding for abstract typename\
\"%s\"\n",get_id(n)),sayhere(id_who(n),1),TYPERRS++;
else current_id=n,t_info(n)=meta_tcheck(t_info(n));
/* placeholder types - no action */
current_id=0;
return; }
if(tag[id_val(n)]==CONSTRUCTOR)return;
/* primitive constructors require no type analysis */
if(id_type(n)!=undef_t) /* meta typecheck spec, if present */
{ current_id=n;
if(tag[id_type(n)]==CONS)
{ /* signature identifier */
if(id_val(n)==UNDEF)SBND=add1(n,SBND);
id_type(n)=redtvars(meta_tcheck(hd[id_type(n)]));
current_id=0;
return; } /* typechecked separately, under TABSTRS */
id_type(n)=redtvars(meta_tcheck(id_type(n)));
current_id=0; }
if(id_val(n)==FREE)return; /* no further analysis required */
if(id_val(n)==UNDEF) /* name specified but not defined */
{ SBND=add1(n,SBND); /* change of policy (as for undefined sigid, above) */
return; } /* now not added to ND, so script can be %included */
r=deps(id_val(n));
while(r!=NIL)
{ if(id_val(hd[r])!=UNDEF&&id_type(hd[r])==undef_t)
/* only defined names without explicitly assigned types
cause dependency */
rhs=add1(hd[r],rhs);
r=tl[r]; }
R=cons(cons(n,rhs),R);
}
word tsort(g) /* topological sort - returns a list of the elements in the domain
of relation g, in an order such that each element is preceded by everything
it depends on */
word g; /* the structure of g is "graph2" see NOTES above */
{ word NP=NIL; /* NP is set of elements with no predecessor */
word g1=g, r=NIL; /* r is result */
g=NIL;
while(g1!=NIL)
{ if(tl[hd[g1]]==NIL)NP=cons(hd[hd[g1]],NP);
else g=cons(hd[g1],g);
g1=tl[g1]; }
while(NP!=NIL)
{ word D=NIL; /* ids to be removed from range of g */
while(NP!=NIL)
{ r=cons(hd[NP],r);
if(tag[hd[NP]]==ID)D=add1(hd[NP],D);
else D=UNION(D,hd[NP]);
NP=tl[NP]; }
g1=g;g=NIL;
while(g1!=NIL)
{ word rhs=setdiff(tl[hd[g1]],D);
if(rhs==NIL)NP=cons(hd[hd[g1]],NP);
else tl[hd[g1]]=rhs,g=cons(hd[g1],g);
g1=tl[g1]; }
}
if(g!=NIL)fprintf(stderr,"error: impossible event in tsort\n");
return(reverse(r));
}
word msc(R) /* collects maximal strong components in R, converting it from "graph1"
to "graph2" form - destructive in R */
word R;
{ word R1=R;
while(R1!=NIL)
{ word *r= &tl[hd[R1]],l=hd[hd[R1]];
if(remove1(l,r))
{ hd[hd[R1]]=cons(l,NIL);
while(*r!=NIL)
{ word n=hd[*r],*R2= &tl[R1];
while(*R2!=NIL&&hd[hd[*R2]]!=n)R2= &tl[*R2]; /* find n-entry in R */
if(*R2!=NIL&&member(tl[hd[*R2]],l))
{ *r=tl[*r]; /* remove n from r */
*R2=tl[*R2]; /* remove n's entry from R */
hd[hd[R1]]=add1(n,hd[hd[R1]]);
}
else r= &tl[*r];
}
}
R1=tl[R1];
}
return(R);
}
word meta_pending=NIL;
word meta_tcheck(t) /* returns type t with synonyms substituted out and checks that
the result is well formed */
word t;
{ word tn=t,i=0;
/* TO DO -- TIDY UP ERROR MESSAGES AND SET ERRLINE (ERRS) IF POSS */
while(iscompound_t(tn))
tl[tn]=meta_tcheck(tl[tn]),i++,tn=hd[tn];
if(tag[tn]==STRCONS)goto L; /* patch to handle free type bindings */
if(tag[tn]!=ID)
{ if(i>0&&(isvar_t(tn)||tn==bool_t||tn==num_t||tn==char_t))
{ TYPERRS++;
if(tag[current_id]==DATAPAIR)
locate_inc(),
printf("badly formed type \""),out_type(t),
printf("\" in binding for \"%s\"\n",(char *)hd[current_id]),
printf("("),out_type(tn),printf(" has zero arity)\n");
else
printf("badly formed type \""),out_type(t),
printf("\" in %s for \"%s\"\n",
id_type(current_id)==type_t?"== binding":"specification",
get_id(current_id)),
printf("("),out_type(tn),printf(" has zero arity)\n"),
sayhere(getspecloc(current_id),1);
sterilise(t); }
return(t); }
if(id_type(tn)==undef_t&&id_val(tn)==UNDEF)
{ TYPERRS++;
if(!member(NT,tn))
{ if(tag[current_id]==DATAPAIR)locate_inc();
printf("undeclared typename \"%s\" ",get_id(tn));
if(tag[current_id]==DATAPAIR)
printf("in binding for %s\n",(char *)hd[current_id]);
else sayhere(getspecloc(current_id),1);
NT=add1(tn,NT); }
return(t); }else
if(id_type(tn)!=type_t||t_arity(tn)!=i)
{ TYPERRS++;
if(tag[current_id]==DATAPAIR)
locate_inc(),
printf("badly formed type \""),out_type(t),
printf("\" in binding for \"%s\"\n",(char *)hd[current_id]);
else
printf("badly formed type \""),out_type(t),
printf("\" in %s for \"%s\"\n",
id_type(current_id)==type_t?"== binding":"specification",
get_id(current_id));
if(id_type(tn)!=type_t)
printf("(%s not defined as typename)\n",get_id(tn));
else printf("(typename %s has arity %ld)\n",get_id(tn),t_arity(tn));
if(tag[current_id]!=DATAPAIR)
sayhere(getspecloc(current_id),1);
sterilise(t);
return(t); }
L:if(t_class(tn)!=synonym_t)return(t);
if(member(meta_pending,tn))
{ TYPERRS++;/* report cycle */
if(tag[current_id]==DATAPAIR)locate_inc();
printf("error: cycle in type \"==\" definition%s ",
meta_pending==NIL?"":"s");
printelement(meta_pending); putchar('\n');
if(tag[current_id]!=DATAPAIR)
sayhere(id_who(tn),1);
longjmp(env1,1); /* fatal error - give up */
/* t_class(tn)=algebraic_t;t_info(tn)=NIL;
/* to make sure we dont fall in here again! */
return(t); }
meta_pending=cons(tn,meta_pending);
tn=NIL;
while(iscompound_t(t))
tn=cons(tl[t],tn),t=hd[t];
t=meta_tcheck(ap_subst(t_info(t),tn));
meta_pending=tl[meta_pending];
return(t);
}
/* needless inefficiency - we recheck the rhs of a synonym every time we
use it */
void sterilise(t) /* to prevent multiple reporting of metatype errors from
namelist :: type */
word t;
{ if(tag[t]==AP)hd[t]=list_t,tl[t]=num_t;
}
word tvcount=1;
#define NTV mktvar(tvcount++)
/* brand new type variable */
#define reset_SUBST (current_id=tvcount>=hashsize?clear_SUBST():0)
void infer_type(x) /* deduces the types of the identifiers in x - no result,
works by filling in id_type fields */
word x; /* x is an "element" */
{ if(tag[x]==ID)
{ word t,oldte=TYPERRS;
current_id=x;
t = subst(etype(id_val(x),NIL,NIL));
if(id_type(x)==undef_t)id_type(x)=redtvars(t);
else /* x already has assigned type */
if(!subsumes(t,instantiate(id_type(x))))
{ TYPERRS++;
printf("incorrect declaration ");
sayhere(getspecloc(x),1); /* or: id_who(x) to locate defn */
printf("specified, "); report_type(x); putchar('\n');
printf("inferred, %s :: ",get_id(x)); out_type(redtvars(t));
putchar('\n'); }
if(TYPERRS>oldte)id_type(x)=wrong_t,
id_val(x)=UNDEF,
ND=add1(x,ND);
reset_SUBST; }
else{ /* recursive group of names */
word x1,oldte,ngt=NIL;
for(x1=x;x1!=NIL;x1=tl[x1])
ngt=cons(NTV,ngt),
id_type(hd[x1])=ap(bind_t,hd[ngt]);
for(x1=x;x1!=NIL;x1=tl[x1])
{ oldte=TYPERRS,
current_id=hd[x1],
unify(tl[id_type(hd[x1])],etype(id_val(hd[x1]),NIL,ngt));
if(TYPERRS>oldte)
id_type(hd[x1])=wrong_t,
id_val(hd[x1])=UNDEF,ND=add1(hd[x1],ND); }
for(x1=x;x1!=NIL;x1=tl[x1])
if(id_type(hd[x1])!=wrong_t)
id_type(hd[x1])=redtvars(ult(tl[id_type(hd[x1])]));
reset_SUBST;
}
}
word hereinc; /* location of currently-being-processed %include */
word lasthereinc;
void mcheckfbs()
{ word ff,formals,n;
lasthereinc=0;
for(ff=FBS;ff!=NIL;ff=tl[ff])
{ hereinc=hd[hd[FBS]];
for(formals=tl[hd[ff]];formals!=NIL;formals=tl[formals])
{ word t=tl[tl[hd[formals]]];
if(t!=type_t)continue;
current_id=hd[tl[hd[formals]]]; /* nb datapair(orig,0) not id */
t_info(hd[hd[formals]])=meta_tcheck(t_info(hd[hd[formals]]));
/*ATNAMES=cons(hd[hd[formals]],ATNAMES?ATNAMES:NIL); */
current_id=0;
}
if(TYPERRS)return; /* to avoid misleading error messages */
for(formals=tl[hd[ff]];formals!=NIL;formals=tl[formals])
{ word t=tl[tl[hd[formals]]];
if(t==type_t)continue;
current_id=hd[tl[hd[formals]]]; /* nb datapair(orig,0) not id */
tl[tl[hd[formals]]]=redtvars(meta_tcheck(t));
current_id=0;
}
/* above double traverse is very inefficient way of doing types first
would be better to have bindings sorted in this order beforehand */
}
/* all imported names must now have their types reduced to
canonical form wrt the parameter bindings */
/* alternative method - put info in ATNAMES, see above and in abstr_check */
/* a problem with this is that types do not print in canonical form */
if(TYPERRS)return;
for(ff=tl[files];ff!=NIL;ff=tl[ff])
for(formals=fil_defs(hd[ff]);formals!=NIL;formals=tl[formals])
if(tag[n=hd[formals]]==ID)
if(id_type(n)==type_t)
{ if(t_class(n)==synonym_t)t_info(n)=meta_tcheck(t_info(n)); }
else id_type(n)=redtvars(meta_tcheck(id_type(n)));
} /* wasteful if many includes */
void redtfr(x) /* ensure types of freeids are in reduced form */
word x;
{ for(;x!=NIL;x=tl[x])
tl[tl[hd[x]]] = id_type(hd[hd[x]]);
}
void checkfbs()
/* FBS is list of entries of form cons(hereinfo,formals) where formals
has elements of form cons(id,cons(datapair(orig,0),type)) */
{ word oldte=TYPERRS,formals;
lasthereinc=0;
for(;FBS!=NIL;FBS=tl[FBS])
for(hereinc=hd[hd[FBS]],formals=tl[hd[FBS]];
formals!=NIL;formals=tl[formals])
{ word t,t1=fix_type(tl[tl[hd[formals]]]);
if(t1==type_t)continue;
current_id=hd[tl[hd[formals]]]; /* nb datapair(orig,0) not id */
t = subst(etype(the_val(hd[hd[formals]]),NIL,NIL));
if(!subsumes(t,instantiate(t1)))
{ TYPERRS++;
locate_inc();
printf("binding for parameter `%s' has wrong type\n",
(char *)hd[current_id]);
printf( "required :: "); out_type(tl[tl[hd[formals]]]);
printf("\n actual :: "); out_type(redtvars(t));
putchar('\n'); }
the_val(hd[hd[formals]])=codegen(the_val(hd[hd[formals]])); }
if(TYPERRS>oldte)
{ /* badly typed parameter bindings, so give up */
extern word SYNERR;
TABSTRS=NT=R=NIL;
printf("compilation abandoned\n");
SYNERR=1; }
reset_SUBST;
}
word fix_type(t) /* substitute out any indirected typenames in t */
word t;
{ switch(tag[t])
{ case AP:
case CONS: tl[t]=fix_type(tl[t]);
hd[t]=fix_type(hd[t]);
default: return(t);
case STRCONS: while(tag[pn_val(t)]!=CONS)t=pn_val(t);/*at most twice*/
return(t);
}
}
void locate_inc()
{ if(lasthereinc==hereinc)return;
printf("incorrect %%include directive ");
sayhere(lasthereinc=hereinc,1);
}
void abstr_mcheck(tabstrs) /* meta-typecheck abstract type declarations */
word tabstrs;
{ while(tabstrs!=NIL)
{ word atnames=hd[hd[tabstrs]],sigids=tl[hd[tabstrs]],rtypes=NIL;
if(cyclic_abstr(atnames))return;
while(sigids!=NIL) /* compute representation types */
{ word rt=rep_t(id_type(hd[sigids]),atnames);
/*if(rt==id_type(hd[sigids]))
printf("abstype declaration error: \"%s\" has a type unrelated to \
the abstraction\n",get_id(hd[sigids])),
sayhere(getspecloc(hd[sigids]),1),
TYPERRS++; /* suppressed June 89, see karen.m, secret.m */
rtypes=cons(rt,rtypes);
sigids=tl[sigids]; }
rtypes=reverse(rtypes);
hd[hd[tabstrs]]=cons(hd[hd[tabstrs]],rtypes);
tabstrs=tl[tabstrs];
}
}
void abstr_check(x) /* typecheck the implementation equations of a type abstraction
with the given signature */
word x;
{ word rtypes=tl[hd[x]],sigids=tl[x];
/*int holdat=ATNAMES;
ATNAMES=shunt(hd[hd[x]],ATNAMES); */
ATNAMES=hd[hd[x]];
txchange(sigids,rtypes); /* install representation types */
/* report_types("concrete signature:\n",sigids); /* DEBUG */
for(x=sigids;x!=NIL;x=tl[x])
{ word t,oldte=TYPERRS;
current_id=hd[x];
t=subst(etype(id_val(hd[x]),NIL,NIL));
if(!subsumes(t,instantiate(id_type(hd[x]))))
{ TYPERRS++;
printf("abstype implementation error\n");
printf("\"%s\" is bound to value of type: ",get_id(hd[x]));
out_type(redtvars(t));
printf("\ntype expected: ");
out_type(id_type(hd[x]));
putchar('\n');
sayhere(id_who(hd[x]),1); }
if(TYPERRS>oldte)
id_type(hd[x])=wrong_t,id_val(hd[x])=UNDEF,ND=add1(hd[x],ND);
reset_SUBST; }
/* restore the abstract types - for "finger" */
for(x=sigids;x!=NIL;x=tl[x],rtypes=tl[rtypes])
if(id_type(hd[x])!=wrong_t)id_type(hd[x])=hd[rtypes];
ATNAMES= /* holdat */ 0;
}
word cyclic_abstr(atnames) /* immediately-cyclic acts of dta are illegal */
word atnames;
{ word x,y=NIL;
for(x=atnames;x!=NIL;x=tl[x])y=ap(y,t_info(hd[x]));
for(x=atnames;x!=NIL;x=tl[x])
if(occurs(hd[x],y))
{ printf("illegal type abstraction: cycle in \"==\" binding%s ",
tl[atnames]==NIL?"":"s");
printelement(atnames); putchar('\n');
sayhere(id_who(hd[x]),1);
TYPERRS++; return(1); }
return(0);
}
void txchange(ids,x) /* swap the id_type of each id with the corresponding type
in the list x */
word ids,x;
{ while(ids!=NIL)
{ word t=id_type(hd[ids]);
id_type(hd[ids])=hd[x],hd[x]=t;
ids=tl[ids],x=tl[x]; }
}
void report_type(x)
word x;
{ printf("%s",get_id(x));
if(id_type(x)==type_t)
if(t_arity(x)>5)printf("(arity %ld)",t_arity(x));
else { word i,j;
for(i=1;i<=t_arity(x);i++)
{ putchar(' ');
for(j=0;j<i;j++)putchar('*'); }
}
printf(" :: ");
out_type(id_type(x));
}
void report_types(header,x)
char *header;
word x;
{ printf("%s",header);
while(x!=NIL)
report_type(hd[x]),putchar(';'),x=tl[x];
putchar('\n');
}
word typesfirst(x) /* rearrange list of ids to put types first */
word x;
{ word *y= &x,z=NIL;
while(*y!=NIL)
if(id_type(hd[*y])==type_t)
z=cons(hd[*y],z),*y=tl[*y];
else y= &tl[*y];
return(shunt(z,x));
}
word rep_t1(T,L) /* computes the representation type corresponding to T, wrt the
abstract typenames in L */
/* will need to apply redtvars to result, see below */
/* if no substitutions found, result is identically T */
word T,L;
{ word args=NIL,t1,new=0;
for(t1=T;iscompound_t(t1);t1=hd[t1])
{ word a=rep_t1(tl[t1],L);
if(a!=tl[t1])new=1;
args=cons(a,args); }
if(member(L,t1))return(ap_subst(t_info(t1),args));
/* call to redtvars removed 26/11/85
leads to premature normalisation of subterms */
if(!new)return(T);
while(args!=NIL)
t1=ap(t1,hd[args]),args=tl[args];
return(t1);
}
word rep_t(T,L) /* see above */
word T,L;
{ word t=rep_t1(T,L);
return(t==T?t:redtvars(t));
}
word type_of(x) /* returns the type of expression x, in reduced form */
word x;
{ word t;
TYPERRS=0;
t=redtvars(subst(etype(x,NIL,NIL)));
fixshows();
if(TYPERRS>0)t=wrong_t;
return(t);
}
word checktype(x) /* is expression x well-typed ? */
/* not currently used */
word x;
{ TYPERRS=0;
etype(x,NIL,NIL);
reset_SUBST;
return(!TYPERRS);
}
#define bound_t(t) (iscompound_t(t)&&hd[t]==bind_t)
#define tf(a,b) ap2(arrow_t,a,b)
#define tf2(a,b,c) tf(a,tf(b,c))
#define tf3(a,b,c,d) tf(a,tf2(b,c,d))
#define tf4(a,b,c,d,e) tf(a,tf3(b,c,d,e))
#define lt(a) ap(list_t,a)
#define pair_t(x,y) ap2(comma_t,x,ap2(comma_t,y,void_t))
word tfnum,tfbool,tfbool2,tfnum2,tfstrstr,tfnumnum,ltchar,
tstep,tstepuntil;
void tsetup()
{ tfnum=tf(num_t,num_t);
tfbool=tf(bool_t,bool_t);
tfnum2=tf(num_t,tfnum);
tfbool2=tf(bool_t,tfbool);
ltchar=lt(char_t);
tfstrstr=tf(ltchar,ltchar);
tfnumnum=tf(num_t,num_t);
tstep=tf2(num_t,num_t,lt(num_t));
tstepuntil=tf(num_t,tstep);
}
word exec_t=0,read_t=0,filestat_t=0; /* set lazily, when used */
word genlstat_t() /* type of %lex state */
{ return(pair_t(num_t,num_t)); }
void genbnft() /* if %bnf used, find out input type of parsing fns */
{ word bnftokenstate=findid("bnftokenstate");
if(bnftokenstate!=NIL&&id_type(bnftokenstate)==type_t)
if(t_arity(bnftokenstate)==0)
bnf_t=t_class(bnftokenstate)==synonym_t?
t_info(bnftokenstate):bnftokenstate;
else printf("warning - bnftokenstate has arity>0 (ignored by parser)\n"),
bnf_t=void_t;
else bnf_t=void_t; /* now bnf_t holds the state type */
bnf_t=ap2(comma_t,ltchar,ap2(comma_t,bnf_t,void_t));
} /* the input type for parsers is lt(bnf_t)
note that tl[hd[tl[bnf_t]]] holds the state type */
extern word col_fn;
void checkcolfn() /* if offside rule used, check col_fn has right type */
{ word t=id_type(col_fn),f=tf(tl[hd[tl[bnf_t]]],num_t);
if(t==undef_t||t==wrong_t
/* will be already reported - do not generate further typerrs
in both cases col_fn will behave as undefined name */
||subsumes(instantiate(t),f))
{ col_fn=0; return; } /* no further action required */
printf("`bnftokenindentation' has wrong type for use in offside rule\n");
printf("type required :: "); out_type(f); putchar('\n');
printf(" actual type :: "); out_type(t); putchar('\n');
sayhere(getspecloc(col_fn),1);
TYPERRS++;
col_fn= -1; /* error flag */
} /* note that all parsing fns get type wrong_t if offside rule used
anywhere and col_fn has wrong type - strictly this is overkill */
word etype(x,env,ngt) /* infer a type for an expression, by using unification */
word x,env; /* env is list of local bindings of variables to types */
word ngt; /* ngt is list of non-generic type variables */
{ word a,b,c,d; /* initialise to 0 ? */
switch(tag[x])
{ case AP: if(hd[x]==BADCASE||hd[x]==CONFERROR)return(NTV);
/* don't type check insides of error messages */
{ word ft=etype(hd[x],env,ngt),at=etype(tl[x],env,ngt),rt=NTV;
if(!unify1(ft,ap2(arrow_t,at,rt)))
{ ft=subst(ft);
if(isarrow_t(ft))
if(tag[hd[x]]==AP&&hd[hd[x]]==G_ERROR)
type_error8(at,tl[hd[ft]]);
else
type_error("unify","with",at,tl[hd[ft]]);
else type_error("apply","to",ft,at);
return(NTV); }
return(rt); }
case CONS: { word ht=etype(hd[x],env,ngt),rt=etype(tl[x],env,ngt);
if(!unify1(ap(list_t,ht),rt))
{ type_error("cons","to",ht,rt);
return(NTV); }
return(rt); }
case LEXER: { word hold=lineptr;
lineptr=hd[tl[tl[hd[x]]]];
tl[tl[hd[x]]]=tl[tl[tl[hd[x]]]];/*discard label(hereinf,-)*/
a=etype(tl[tl[hd[x]]],env,ngt);
while((x=tl[x])!=NIL)
{ lineptr=hd[tl[tl[hd[x]]]];
tl[tl[hd[x]]]=tl[tl[tl[hd[x]]]];/*discard label... */
if(!unify1(a,b=etype(tl[tl[hd[x]]],env,ngt)))
{ type_error7(a,b);
lineptr=hold;
return(NTV); }
}
lineptr=hold;
return(tf(ltchar,lt(a))); }
case TCONS: return(ap2(comma_t,etype(hd[x],env,ngt),
etype(tl[x],env,ngt)));
case PAIR: return(ap2(comma_t,etype(hd[x],env,ngt),
ap2(comma_t,etype(tl[x],env,ngt),void_t)));
case DOUBLE:
case INT: return(num_t);
case ID: a=env;
while(a!=NIL) /* take local binding, if present */
if(hd[hd[a]]==x)
return(linst(tl[hd[a]]=subst(tl[hd[a]]),ngt));
else a=tl[a];
a=id_type(x); /* otherwise pick up global binding */
if(bound_t(a))return(tl[a]);
if(a==type_t)type_error1(x);
if(a==undef_t)
{ extern word commandmode;
if(commandmode)type_error2(x);
else
if(!member(ND,x)) /* report first occurrence only */
{ if(lineptr)sayhere(lineptr,0);
else if(tag[current_id]==DATAPAIR) /* see checkfbs */
locate_inc();
printf("undefined name \"%s\"\n",get_id(x));
ND=add1(x,ND); }
return(NTV); }
if(a==wrong_t)return(NTV);
return(instantiate(ATNAMES?rep_t(a,ATNAMES):a));
case LAMBDA: a=NTV; b=NTV;
d=cons(a,ngt);
c=conforms(hd[x],a,env,d);
if(c==-1||!unify(b,etype(tl[x],c,d)))return(NTV);
return(tf(a,b));
case LET: { word e,def=hd[x];
a=NTV,e=conforms(dlhs(def),a,env,cons(a,ngt));
current_id=cons(dlhs(def),current_id);
c=lineptr; lineptr=dval(def);
b = unify(a,etype(dval(def),env,ngt));
lineptr=c;
current_id=tl[current_id];
if(e==-1||!b)return(NTV);
return(etype(tl[x],e,ngt)); }
case LETREC: { word e=env,s=NIL;
a=NIL; c=ngt;
for(d=hd[x];d!=NIL;d=tl[d])
if(dtyp(hd[d])==undef_t)
a=cons(hd[d],a), /* unspecified defs */
dtyp(hd[d])=(b=NTV),
c=cons(b,c), /* collect non-generic tvars */
e=conforms(dlhs(hd[d]),b,e,c);
else dtyp(hd[d])=meta_tcheck(dtyp(hd[d])),
/* should do earlier, and locate errs properly*/
s=cons(hd[d],s), /* specified defs */
e=cons(cons(dlhs(hd[d]),dtyp(hd[d])),e);
if(e==-1)return(NTV);
b=1;
for(;a!=NIL;a=tl[a])
{ current_id=cons(dlhs(hd[a]),current_id);
d=lineptr; lineptr=dval(hd[a]);
b &= unify(dtyp(hd[a]),etype(dval(hd[a]),e,c));
lineptr=d; current_id=tl[current_id]; }
for(;s!=NIL;s=tl[s])
{ current_id=cons(dlhs(hd[s]),current_id);
d=lineptr; lineptr=dval(hd[s]);
if(!subsumes(a=etype(dval(hd[s]),e,ngt),
linst(dtyp(hd[s]),ngt)))
/* would be better to set lineptr to spec here */
b=0,type_error6(dlhs(hd[s]),dtyp(hd[s]),a);
lineptr=d; current_id=tl[current_id]; }
if(!b)return(NTV);
return(etype(tl[x],e,ngt)); }
case TRIES: { word hold=lineptr;
a=NTV;
x=tl[x];
while(x!=NIL&&(lineptr=hd[hd[x]],
unify(a,etype(tl[hd[x]],env,ngt)))
)x=tl[x];
lineptr=hold;
if(x!=NIL)return(NTV);
return(a); }
case LABEL: { word hold=lineptr,t;
lineptr=hd[x];
t=etype(tl[x],env,ngt);
lineptr=hold;
return(t); }
case STARTREADVALS: if(tl[x]==0)
hd[x]=lineptr, /* insert here-info */
tl[x]=NTV,
showchain=cons(x,showchain);
return(tf(ltchar,lt(tl[x])));
case SHOW: hd[x]=lineptr; /* insert here-info */
showchain=cons(x,showchain);
return(tf(tl[x]=NTV,ltchar));
case SHARE: if(tl[x]==undef_t)
{ word h=TYPERRS;
tl[x]=subst(etype(hd[x],env,ngt));
if(TYPERRS>h)hd[x]=UNDEF,tl[x]=wrong_t; }
if(tl[x]==wrong_t)
{ TYPERRS++; return(NTV); }
return(tl[x]);
case CONSTRUCTOR: a=id_type(tl[x]);
return(instantiate(ATNAMES?rep_t(a,ATNAMES):a));
case UNICODE: return(char_t);
case ATOM: if(x<256)return(char_t);
switch(x)
{
case S:a=NTV,b=NTV,c=NTV;
d=tf3(tf2(a,b,c),tf(a,b),a,c);
return(d);
case K:a=NTV,b=NTV;
return(tf2(a,b,a));
case Y:a=NTV;
return(tf(tf(a,a),a));
case C:a=NTV,b=NTV,c=NTV;
return(tf3(tf2(a,b,c),b,a,c));
case B:a=NTV,b=NTV,c=NTV;
return(tf3(tf(a,b),tf(c,a),c,b));
case FORCE:
case G_UNIT:
case G_RULE:
case I:a=NTV;
return(tf(a,a));
case G_ZERO:return(NTV);
case HD:a=NTV;
return(tf(lt(a),a));
case TL:a=lt(NTV);
return(tf(a,a));
case BODY:a=NTV,b=NTV;
return(tf(ap(a,b),a));
case LAST:a=NTV,b=NTV;
return(tf(ap(a,b),b));
case S_p:a=NTV,b=NTV;
c=lt(b);
return(tf3(tf(a,b),tf(a,c),a,c));
case U:
case U_: a=NTV,b=NTV;
c=lt(a);
return(tf2(tf2(a,c,b),c,b));
case Uf: a=NTV,b=NTV,c=NTV;
return(tf2(tf2(tf(a,b),a,c),b,c));
case COND: a=NTV;
return(tf3(bool_t,a,a,a));
case EQ:case GR:case GRE:
case NEQ: a=NTV;
return(tf2(a,a,bool_t));
case NEG: return(tfnum);
case AND:
case OR: return(tfbool2);
case NOT: return(tfbool);
case MERGE:
case APPEND: a=lt(NTV);
return(tf2(a,a,a));
case STEP: return(tstep);
case STEPUNTIL: return(tstepuntil);
case MAP: a=NTV; b=NTV;
return(tf2(tf(a,b),lt(a),lt(b)));
case FLATMAP: a=NTV,b=lt(NTV);
return(tf2(tf(a,b),lt(a),b));
case FILTER: a=NTV; b=lt(a);
return(tf2(tf(a,bool_t),b,b));
case ZIP: a=NTV; b=NTV;
return(tf2(lt(a),lt(b),lt(pair_t(a,b))));
case FOLDL: a=NTV; b=NTV;
return(tf3(tf2(a,b,a),a,lt(b),a));
case FOLDL1: a=NTV;
return(tf2(tf2(a,a,a),lt(a),a));
case LIST_LAST: a=NTV;
return(tf(lt(a),a));
case FOLDR: a=NTV; b=NTV;
return(tf3(tf2(a,b,b),b,lt(a),b));
case MATCHINT:
case MATCH: a=NTV,b=NTV;
return(tf3(a,b,a,b));
case TRY: a=NTV;
return(tf2(a,a,a));
case DROP:
case TAKE: a=lt(NTV);
return(tf2(num_t,a,a));
case SUBSCRIPT:a=NTV;
return(tf2(num_t,lt(a),a));
case P: a=NTV;
b=lt(a);
return(tf2(a,b,b));
case B_p: a=NTV,b=NTV;
c=lt(a);
return(tf3(a,tf(b,c),b,c));
case C_p: a=NTV,b=NTV;
c=lt(b);
return(tf3(tf(a,b),c,a,c));
case S1: a=NTV,b=NTV,c=NTV,d=NTV;
return(tf4(tf2(a,b,c),tf(d,a),tf(d,b),d,c));
case B1: a=NTV,b=NTV,c=NTV,d=NTV;
return(tf4(tf(a,b),tf(c,a),tf(d,c),d,b));
case C1: a=NTV,b=NTV,c=NTV,d=NTV;
return(tf4(tf2(a,b,c),tf(d,a),b,d,c));
case SEQ: a=NTV,b=NTV;
return(tf2(a,b,b));
case ITERATE1:
case ITERATE: a=NTV;
return(tf2(tf(a,a),a,lt(a)));
case EXEC: { if(!exec_t)
a=ap2(comma_t,ltchar,ap2(comma_t,num_t,void_t)),
exec_t=tf(ltchar,ap2(comma_t,ltchar,a));
return(exec_t); }
case READBIN:
case READ: { if(!read_t)
read_t=tf(char_t,ltchar);
/* $- is ap(READ,0) */
return(read_t); }
case FILESTAT: { if(!filestat_t)
filestat_t=tf(ltchar,pair_t(pair_t(num_t,num_t),num_t));
return(filestat_t); }
case FILEMODE:
case GETENV:
case NB_STARTREAD:
case STARTREADBIN:
case STARTREAD: return(tfstrstr);
case GETARGS: return(tf(char_t,lt(ltchar)));
case SHOWHEX:
case SHOWOCT:
case SHOWNUM: return(tf(num_t,ltchar));
case SHOWFLOAT:
case SHOWSCALED: return(tf2(num_t,num_t,ltchar));
case NUMVAL: return(tf(ltchar,num_t));
case INTEGER: return(tf(num_t,bool_t));
case CODE: return(tf(char_t,num_t));
case DECODE: return(tf(num_t,char_t));
case LENGTH: return(tf(lt(NTV),num_t));
case ENTIER_FN: case ARCTAN_FN: case EXP_FN: case SIN_FN:
case COS_FN: case SQRT_FN: case LOG_FN: case LOG10_FN:
return(tfnumnum);
case MINUS:case PLUS:case TIMES:case INTDIV:case FDIV:
case MOD:case POWER: return(tfnum2);
case True: case False: return(bool_t);
case NIL: a=lt(NTV);
return(a);
case NILS: return(ltchar);
case MKSTRICT: a=NTV;
return(tf(char_t,tf(a,a)));
/* the following are not the true types of the G_fns, which have the action
Ai->lt(bnf_t)->(B:lt(bnf_t))
here represented by the type Ai->B. G_CLOSE interfaces the parser fns to
the outside world */
case G_ALT: a=NTV;
return(tf2(a,a,a));
case G_ERROR: a=NTV;
return(tf2(a,tf(lt(bnf_t),a),a));
case G_OPT:
case G_STAR: a=NTV;
return(tf(a,lt(a)));
case G_FBSTAR: a=NTV; b=tf(a,a);
return(tf(b,b));
case G_SYMB: return(tfstrstr);
case G_ANY: return(ltchar);
case G_SUCHTHAT: return(tf(tf(ltchar,bool_t),ltchar));
case G_END: return(lt(bnf_t));
case G_STATE: return(tl[hd[tl[bnf_t]]]);
case G_SEQ: a=NTV; b=NTV;
return(tf2(a,tf(a,b),b));
/* G_RULE has same type as I */
case G_CLOSE: a=NTV;
if(col_fn) /* offside rule used */
if(col_fn== -1) /* arbitrary flag */
TYPERRS++; /*overkill, see note on checkcolfn*/
else checkcolfn();
return(tf3(ltchar,a,lt(bnf_t),a));
case OFFSIDE: return(ltchar);
/* pretend, used by indent, see prelude */
case FAIL: /* compiled from last guard on rhs */
case CONFERROR:
case BADCASE:
case UNDEF: return(NTV);
case ERROR: return(tf(ltchar,NTV));
default: printf("do not know type of ");
out(stdout,x);
putchar('\n');
return(wrong_t);
}
default: printf("unexpected tag in etype ");
out(stdout,tag[x]);
putchar('\n');
return(wrong_t);
}
}
word rhs_here(r)
word r;
{ if(tag[r]==LABEL)return(hd[r]);
if(tag[r]==TRIES)return(hd[hd[lastlink(tl[r])]]);
return(0); /* something wrong */
} /* efficiency hack, sometimes we set lineptr to rhs, can extract here_info
as above when needed */
word conforms(p,t,e,ngt) /* returns new environment of local type bindings obtained
by conforming pattern p to type t; -1 means failure */
word p,t,e,ngt;