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#!/usr/bin/env nomsu -V1
#
This file contains basic error reporting code
use "core/metaprogramming.nom"
compile [traceback] to: Lua value "debug.traceback()"
compile [traceback %] to: Lua value "debug.traceback('', \(% as lua expr))"
compile [barf] to: Lua "error(nil, 0);"
compile [barf %msg] to: Lua "error(\(%msg as lua expr), 0);"
compile [assume %condition] to
lua> "local \%assumption = 'Assumption failed: '..tostring(nomsu:tree_to_nomsu(\%condition))"
return
Lua ".."
if not \(%condition as lua expr) then
error(\(quote "\%assumption"), 0)
end
compile [assume %condition or barf %message] to
Lua ".."
if not \(%condition as lua expr) then
error(\(%message as lua expr), 0)
end
# Try/except
compile [..]
try %action and if it succeeds %success or if it barfs %msg %fallback
try %action and if it barfs %msg %fallback or if it succeeds %success
..to
Lua ".."
do
local fell_through = false
local err, erred = nil, false
local ok, ret = xpcall(function()
\(%action as lua statements)
fell_through = true
end, function(\(%msg as lua expr))
local ok, ret = pcall(function()
\(%fallback as lua statements)
end)
if not ok then err, erred = ret, true end
end)
if ok then
\(%success as lua statements)
if not fell_through then
return ret
end
elseif erred then
error(err, 0)
end
end
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
parse [..]
try %action and if it succeeds %success or if it barfs %fallback
try %action and if it barfs %fallback or if it succeeds %success
..as: try %action and if it succeeds %success or if it barfs (=lua "") %fallback
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
parse [try %action] as
try %action and if it succeeds: do nothing
..or if it barfs: do nothing
parse [try %action and if it barfs %fallback] as
try %action and if it succeeds: do nothing
..or if it barfs %fallback
parse [try %action and if it barfs %msg %fallback] as
try %action and if it succeeds: do nothing
..or if it barfs %msg %fallback
parse [try %action and if it succeeds %success] as
try %action and if it succeeds %success or if it barfs: do nothing
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