**Nest Programming Language**


Nest is a language on top of TCL. It was originally meant to be used for a persistence package for OpenACS (http://www.openacs.org) but the time has passed. The actual code does not exceed 500 lines. Its output can be compiled into C code (or any other target language). In other words, nest provides a language to write other languages. 

You can find the "nest" package here: http://openacs.org/storage/download/nest-1.0.tar.bz2?file_id=4205606%|%nest-1.0%|%

You may find my templating presentation in EuroTCL 2013 relevant:
http://www.tcl.tk/community/tcl2013/EuroTcl/presentations/EuroTcl2013-Demetriou-WebTemplating.pdf

You can follow the development here:
https://github.com/neophytos-sk/nest

Dependencies:

   * TCL (http://www.tcl.tk)

   * tDOM (https://tdom.github.com)

History:

   * nest-1.0 (2014-11-30) - alias/forward, inst/decl mode, class/object aliases, struct/slot, template/pair - 322 lines

Notes:

   * check out the definition of the struct construct in nest, I think it's cool:

======
    alias {object} with_mode {inst} nest {type_helper}

    alias {class} with_mode {decl} nest

    meta {class} {class {object}} {struct} {
        varchar name
        varchar type
        varchar nsp
        varchar default_value = ""

        multiple struct slot = {} {
            varchar name
            varchar type
            varchar meta
            varchar default_value = ""
            bool optional_p = false
            varchar container = ""
        }

        varchar pk
        bool is_final_if_no_scope

    }
======

   * also, check the pair construct, nest-style:

======
    template {pair} {typefirst typesecond} {
        ${typefirst} {first}
        ${typesecond} {second}
    } {type_helper}
======

   * check out its [lambda] proc:

======
    proc lambda {params body args} {

        set {llength_params} [llength ${params}]
        set {llength_args} [llength ${args}]

        if { ${llength_params} - 1 <= ${llength_args} } {
            set {last_param} [lindex ${params} {end}]
            if { ${llength_params} == ${llength_args} || ${last_param} eq {args} } {
                unset {llength_params} {llength_args}
                return [uplevel 0 ${body} [if {${params} eq {}} {
                    # llength_params == 0 and llength_args == 0
                    unset {last_param} {params} {body} {args}
                } elseif { ${last_param} ne {args} } {
                    # llength_params == llength_args
                    lassign ${args} {*}[concat ${params} \
                        [unset {last_param} {params} {body} {args}]]
                } else {
                    # (llength_params - 1 <= llength_args) and last_param eq {args}
                    set {args} [lassign ${args} {*}[lrange [concat ${params} \
                        [unset {last_param} {params} {body} {args}]] 0 {end-1}]]
                    set {} {}
                }]]
            }
        }

        if { ${args} eq {} } {
            return [list {lambda} ${params} ${body}]
        } elseif {${llength_params} >= ${llength_args}} {
            return \
                [list {lambda} [lrange ${params} ${llength_args} {end}] \
                    [concat \
                        [list lassign ${args} \
                            {*}[lrange ${params} 0 [expr {${llength_args} - 1}]]] 
                    { ; } 
                    ${body}]]
        } else {
            error "lambda: more args than params"
        }

    } 
======

("before the chicken and the egg, it was the nest")

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