#lang scribble/manual

@title{BSL Primitive Operations}

Pyret's BSL provides almost all of the same primitive operations that
@tt{htdp/bsl+} (i.e., @emph{Beginning Student Language with list abbreviations})
provides.
Additionally, since Pyret
does not have @tt{require}, it also provides all functions found in the
@tt{2htdp/image}, @tt{2htdp/batch-io}, and @tt{2htdp/universe} teachpacks.

Some of these function names cannot be parsed properly in Pyret
(e.g., @tt{string-length} would parse as @tt{(- string length)}).
Therefore, there are some renaming conventions to be aware of.

Hyphens and slashes are converted to underscores. So, the function
@tt{string-length} becomes @tt{string_length}. Predicates go from
being @tt{foo?} to @tt{is_foo}, so @tt{number?} becomes @tt{is_number}.
Functions like @tt{number->string} become @tt{number_to_string}.
The only functions that are outliers are shown below:

@verbatim|{
string<?           => string_lt
string<=?          => string_leq
string=?           => string_equal
string>=?          => string_geq
string>?           => string_lt

string-ci<?        => string_ci_lt
string-ci<=?       => string_ci_leq
string-ci=?        => string_ci_equal
string-ci>=?       => string_ci_geq
string-ci>?        => string_ci_gt

string-lower-case? => string_is_lower_case
string-upper-case? => string_is_upper_case
string-alphabetic? => string_is_alphabetic
string-whitespace? => string_is_whitespace
string-numeric?    => string_is_numeric

string-contains?   => string_contains

=~                 => approx_equal
equal?             => equal
}|

The @tt{car} and @tt{cdr} functions are not provided (use
@tt{first} and @tt{rest} instead), and there is no
@tt{is_cons} function (use @tt{is_list}). This is because
Pyret does not support dotted pairs. Additionally, there
is no such thing as a `character` in Pyret, so there are
no function involving characters (except for
@tt{string_ref}, which returns a one-character string).

Finally, with the exception of images, structs no longer
have accessor functions, so there is no @tt{posn_x} and
@tt{posn_y} function (use `.` instead). The dot operator
will work with images, but functions might be more readable.

The @tt{eq} and @tt{eqv} functions are not available
(and therefore neither are @tt{memq}, @tt{memv}, @tt{remq},
and @tt{remv}).