Evaluator Functions

function evaluate/evaluate src [args]

evaluate Idio source code src in the context of evaluation environment eenv and return intermediate code for the code generator

Param src:

Idio source code

Type src:

Abstract Syntax Tree

Param eenv:

evaluation environment, defaults to a new instance

Type eenv:

struct-instance, optional

function symbol-value sym mod [default]

Return the value of sym in mod or default if supplied

Param sym:

symbol to query

Type sym:

symbol

Param mod:

module to query

Type mod:

module or name

Param default:

(optional) value to return if sym is not defined in mod

Type defined:

any

Return:

value or default

template cond-expand clauses

cond-expand reduces clauses to the first cond_expand_clause where the clause’s feature_requirement is true

cond-expand is a template and so, in effect, it reduces the set of clauses supplied to just the first that is true.

The feature_requirement for each clause in clauses is constructed from the presence of feature_identifiers or logical combinations of those features. The features themselves are set by idio or can be augmented by users.

The clauses for cond-expand are interpreted as the (SRFI-0) grammar conditional_expansion_form:

conditional_expansion_form ::=    (cond-expand cond_expand_clause+)
                                | (cond-expand cond_expand_clause* (else expression*))
cond_expand_clause         ::=  (feature_requirement expression*)
feature_requirement        ::=    feature_identifier
                                | (and feature_requirement*)
                                | (or  feature_requirement*)
                                | (not feature_requirement)
feature_identifier         ::=  a symbol or string, see below

Example:

Several tests of standard library calls in libc differ between operating systems. We can specialize as appropriate and cond-expand results in just a single libc-wrap-error-load expression in the byte code.

(cond-expand
 ((or "uname/sysname/FreeBSD"
      "uname/sysname/OpenBSD"
      "uname/sysname/Darwin") {
   libc-wrap-error-load "libc-wrap-errors/EGID-set-invalid-gid.idio" "Operation not permitted" EPERM "setegid"
 })
 (else {
   libc-wrap-error-load "libc-wrap-errors/EGID-set-invalid-gid.idio" "Invalid argument" EINVAL "setegid"
 })
)

See also

Idio Features and %add-feature

function %add-feature f

add feature f to Idio features

Param f:

feature to add

Type f:

symbol or string

Return:

new list of features

Last built at 2024-12-21T07:10:37Z+0000 from 62cca4c (dev) for Idio 0.3.b.6