strings.chr

:- module(strings, [t/2, type(tags/0)]).
:- use_module(prelude).
:- use_module(library(strings)).
:- chr_constraint t/2.
:- chr_type tags ---> concat_basic ; concat_empty_l ; concat_empty_r ; concat_both ; len_zero ; len_short ; len_basic ; len_unicode ; upper_basic ; upper_already ; upper_empty ; upper_unicode ; lower_basic ; lower_mixed ; lower_empty.

t(concat_basic, R)    <=> R is string_concat("foo", "bar").
t(concat_empty_l, R)  <=> R is string_concat("", "abc").
t(concat_empty_r, R)  <=> R is string_concat("abc", "").
t(concat_both, R)     <=> R is string_concat("", "").

t(len_zero, R)        <=> R is string_length("").
t(len_short, R)       <=> R is string_length("a").
t(len_basic, R)       <=> R is string_length("hello").
t(len_unicode, R)     <=> R is string_length("café").

t(upper_basic, R)     <=> R is string_upper("Hello").
t(upper_already, R)   <=> R is string_upper("ABC").
t(upper_empty, R)     <=> R is string_upper("").
t(upper_unicode, R)   <=> R is string_upper("café").

t(lower_basic, R)     <=> R is string_lower("HELLO").
t(lower_mixed, R)     <=> R is string_lower("HelloWorld").
t(lower_empty, R)     <=> R is string_lower("").