term* normalize_fuel_datatype(context *Sigma, typing_context* Delta, term* t, int fuel) {
term* ans = make_datatype_term(variable_dup(t->var), t->num_args);
int i;
for (i = 0; i < t->num_args; i++) {
ans->args[i] = normalize_fuel(Sigma, Delta, t->args[i], fuel-1);
}
return ans;
}
/*
invariant: no sharing between returned term and *any* arguments.
the caller must free the result.
*/
term* substitute(variable* from, term* to, term* haystack) {
if (haystack == NULL) return NULL;
check(from != NULL && to != NULL, "substitute requires non-NULL arguments");
check(term_locally_well_formed(to), "substitute requires %W to be locally well-formed", to, print_term);
check(term_locally_well_formed(haystack),"substitute requires %W to be locally well-formed", haystack, print_term);
switch(haystack->tag) {
case VAR:
if (variable_equal(from, haystack->var)) {
return term_dup(to);
} else {
return term_dup(haystack);
}
case HOLE:
return term_dup(haystack);
case LAM:
if (variable_equal(from, haystack->var)) {
return make_lambda(variable_dup(haystack->var),
substitute(from, to, haystack->left),
term_dup(haystack->right));
} else {
if (is_free(haystack->var, to)) {
variable *g = gensym(haystack->var->name);
term *tg = make_var(g);
term* new_haystack = make_lambda(variable_dup(g), term_dup(haystack->left),
substitute(haystack->var, tg, haystack->right));
free_term(tg);
term* ans = substitute(from, to, new_haystack);
free_term(new_haystack);
return ans;
}
return make_lambda(variable_dup(haystack->var),
substitute(from, to, haystack->left),
substitute(from, to, haystack->right));
}
case PI:
if (variable_equal(from, haystack->var)) {
return make_pi(variable_dup(haystack->var),
substitute(from, to, haystack->left),
term_dup(haystack->right));
} else {
if (is_free(haystack->var, to)) {
variable *g = gensym(haystack->var->name);
term *tg = make_var(g);
term* new_haystack = make_pi(variable_dup(g), term_dup(haystack->left),
substitute(haystack->var, tg, haystack->right));
free_term(tg);
term* ans = substitute(from, to, new_haystack);
free_term(new_haystack);
return ans;
}
return make_pi(variable_dup(haystack->var),
substitute(from, to, haystack->left),
substitute(from, to, haystack->right));
}
case APP:
return make_app(substitute(from, to, haystack->left),
substitute(from, to, haystack->right));
case TYPE:
return term_dup(haystack);
case DATATYPE:
{
term* ans = make_datatype_term(variable_dup(haystack->var),
haystack->num_params, haystack->num_indices);
#define SUB_VEC(dst, src, n) do { \
int __i; \
for (__i = 0; __i < n; __i++) { \
dst[__i] = substitute(from, to, src[__i]); \
} \
} while(0)
SUB_VEC(ans->params, haystack->params, haystack->num_params);
SUB_VEC(ans->indices, haystack->indices, haystack->num_indices);
return ans;
}
case INTRO:
{
term* ans = make_intro(variable_dup(haystack->var),
substitute(from, to, haystack->left),
haystack->num_args,
haystack->num_params,
haystack->num_indices);
SUB_VEC(ans->args, haystack->args, haystack->num_args);
SUB_VEC(ans->params, haystack->params, haystack->num_params);
SUB_VEC(ans->indices, haystack->indices, haystack->num_indices);
return ans;
}
case ELIM:
{
term* ans = make_elim(variable_dup(haystack->var), haystack->num_args, haystack->num_params, haystack->num_indices);
SUB_VEC(ans->args, haystack->args, haystack->num_args);
SUB_VEC(ans->params, haystack->params, haystack->num_params);
SUB_VEC(ans->indices, haystack->indices, haystack->num_indices);
return ans;
}
case IMPLICIT:
return term_dup(haystack);
default:
sentinel("malformed term with tag %d", haystack->tag);
}
error:
return NULL;
}
