diff options
Diffstat (limited to 'lib/core/control_flow.nom')
| -rw-r--r-- | lib/core/control_flow.nom | 130 |
1 files changed, 57 insertions, 73 deletions
diff --git a/lib/core/control_flow.nom b/lib/core/control_flow.nom index fafc45d..481507f 100644 --- a/lib/core/control_flow.nom +++ b/lib/core/control_flow.nom @@ -1,5 +1,6 @@ -#!/usr/bin/env nomsu -V6.15.13.8 -# +#!/usr/bin/env nomsu -V7.0.0 + +### This file contains compile-time actions that define basic control flow structures like "if" statements and loops. @@ -8,12 +9,12 @@ use "core/operators" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -# No-Op +### No-Op test: do nothing (do nothing) compiles to "" -# Conditionals +### Conditionals test: if (no): fail "conditional fail" @@ -48,8 +49,8 @@ test: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -# Conditional expression (ternary operator) -# Note: this uses a function instead of "(condition and if_expr or else_expr)" +### Conditional expression (ternary operator) +### Note: this uses a function instead of "(condition and if_expr or else_expr)" because that breaks if $if_expr is falsey, e.g. "x < 5 and false or 99" test: assume ((1 if (yes) else 2) == 1) @@ -61,7 +62,7 @@ test: $when_false_expr unless $condition else $when_true_expr $when_false_expr unless $condition then $when_true_expr ] all compile to: - # If $when_true_expr is guaranteed to be truthy, we can use Lua's idiomatic + ### If $when_true_expr is guaranteed to be truthy, we can use Lua's idiomatic equivalent of a conditional expression: (cond and if_true or if_false) if {.Text, .List, .Dict, .Number}.($when_true_expr.type): return Lua (" @@ -69,7 +70,7 @@ test: ..\($when_false_expr as lua expr)) ") ..else: - # Otherwise, need to do an anonymous inline function (yuck, too bad lua + ### Otherwise, need to do an anonymous inline function (yuck, too bad lua doesn't have a proper ternary operator!) To see why this is necessary consider: (random()<.5 and false or 99) return Lua (" @@ -84,7 +85,7 @@ test: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -# GOTOs +### GOTOs test: $i = 0 --- $loop --- @@ -112,7 +113,7 @@ test: ) ") -# Basic loop control +### Basic loop control (stop $var) compiles to: if $var: return Lua "goto stop_\($var as lua identifier)" @@ -128,7 +129,7 @@ test: (---stop $var ---) compiles to "::stop_\($var as lua identifier)::" (---next $var ---) compiles to "::continue_\($var as lua identifier)::" -# While loops +### While loops test: $x = 0 repeat while ($x < 10): $x += 1 @@ -149,7 +150,7 @@ test: \($body as lua) ") - if ($body has subtree \(do next)): + if ($body, contains `(do next)): $lua, add "\n ::continue::" $lua, add "\nend --while-loop" @@ -160,12 +161,12 @@ test: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -# For-each loop (lua's "ipairs()") +### For-each loop (lua's "ipairs()") (for $var in $iterable $body) compiles to: unless $var: at (this tree) fail "No var here" - # This uses Lua's approach of only allowing loop-scoped variables in a loop + ### This uses Lua's approach of only allowing loop-scoped variables in a loop if (($var.type == "Action") and ($var.stub == "1 =")): [$key, $value] = [$var.1, $var.3] ..else: @@ -174,7 +175,7 @@ test: unless $value: at (this tree) fail "No value here" - # Numeric loop: + ### Numeric loop: if (($iterable.type == "Action") and (($iterable, get stub) == "1 to")): [$start, $stop] = [$iterable.1, $iterable.3] $loop = @@ -191,7 +192,7 @@ test: go to (loop set) - # Numeric loop with step: + ### Numeric loop with step: if (($iterable.type == "Action") and (($iterable, get stub) == "1 to 2 by")): [$start, $stop, $step] = [$iterable.1, $iterable.3, $iterable.5] $loop = @@ -208,21 +209,19 @@ test: go to (loop set) - # for $ in (...): + ### for $ in (...): if $key: $loop = Lua (" - for \($key as lua identifier),\($value as lua identifier) in pairs(\($iterable as lua expr)) do + for \($key as lua identifier),\($value as lua identifier) in pairs(\ + ..\($iterable as lua expr)) do ") ..else: $loop = - Lua (" - for _i,\($value as lua identifier) in _ipairs(\($iterable as lua expr)) do - ") - + Lua "for _i,\($value as lua identifier) in _ipairs(\($iterable as lua expr)) do" --- (loop set) --- - # TODO: don't always wrap in block + ### TODO: don't always wrap in block $lua = Lua (" do -- for-loop @@ -230,37 +229,31 @@ test: \; ") $lua, add ($body as lua) - if ($body has subtree \(do next)): + if ($body, contains `(do next)): $lua, add "\n ::continue::" - if ($key and ($body has subtree \(do next $key))): - $lua, add "\n " (\(---next $key ---) as lua) + if ($key and ($body, contains ("Action" tree with "do" "next" $key))): + $lua, add "\n " (("Action" tree with "---" "next" $key "---") as lua) - if ($body has subtree \(do next $value)): - $lua, add "\n " (\(---next $value ---) as lua) + if ($body, contains ("Action" tree with "do" "next" $value)): + $lua, add "\n " (("Action" tree with "---" "next" $value "---") as lua) $lua, add "\n end" - if ($key and ($body has subtree \(stop $key))): - $lua, add "\n " (\(---stop $key ---) as lua) + if ($key and ($body, contains ("Action" tree with "stop" $key))): + $lua, add "\n " (("Action" tree with "---" "stop" $key "---") as lua) - if ($body has subtree \(stop $value)): - $lua, add "\n " (\(---stop $value ---) as lua) + if ($body, contains ("Action" tree with "stop" $value)): + $lua, add "\n " (("Action" tree with "---" "stop" $value "---") as lua) $lua, add "\nend -- for-loop" - $lua, remove free vars [($value as lua identifier, text), $key and ($key as lua identifier, text)] + $lua, remove free vars + [($value as lua identifier, text), $key and ($key as lua identifier, text)] return $lua -# TODO: remove these shims: -(for $var in $iterable at $i $body) parses as - for ($i = $var) in $iterable $body - -(for $k = $v in $iterable $body) parses as - for ($k = $v) in $iterable $body - test: $d = {.a = 10, .b = 20, .c = 30, .d = 40, .e = 50} $result = [] - for $k = $v in $d: + for ($k = $v) in $d: if ($k == "a"): do next $k @@ -270,7 +263,7 @@ test: $result, add "\$k = \$v" assume (($result sorted) == ["c = 30", "d = 40", "e = 50"]) -# Numeric range for loops +### Numeric range for loops test: assume ([: for $ in (1 to 5): add $] == [1, 2, 3, 4, 5]) assume ([: for $ in (1 to 5 by 2): add $] == [1, 3, 5]) @@ -286,16 +279,7 @@ test: stop $outer assume ($nums == [1, -2, 3, -2, 3, 4, 3, 4, 5]) -# TODO: These are shims, and should be phased out: -[ - for $var in $start to $stop by $step $body - for $var in $start to $stop via $step $body -] all parse as (for $var in ($start to $stop by $step) $body) - -(for $var in $start to $stop $body) parses as - for $var in ($start to $stop) $body - -# repeat $n times is a shorthand: +### repeat $n times is a shorthand: test: $x = 0 repeat 5 times: @@ -319,7 +303,7 @@ test: else: fail "bad conditional" -# Multi-branch conditional (if..elseif..else) +### Multi-branch conditional (if..elseif..else) (when $body) compiles to: $code = (Lua "") $clause = "if" @@ -332,7 +316,7 @@ test: for $line in $body: unless - (($line.type == "Action") and ((#$line) >= 2)) and + (($line.type == "Action") and (#$line >= 2)) and $line.(#$line) is "Block" syntax tree ..: at $line fail (" @@ -341,14 +325,14 @@ test: ..or "else" followed by a block. ") $action = $line.(#$line) - if (($line.1 == "else") and ((#$line) == 2)): + if (($line.1 == "else") and (#$line == 2)): unless $else_allowed: at $line fail (" Compile error: You can't have two 'else' blocks. Hint: Merge all of the 'else' blocks together. ") - unless ((#"\$code") > 0): + unless (#"\$code" > 0): at $line fail (" Compile error: You can't have an 'else' block without a preceding condition. Hint: If you want the code in this block to always execute, you don't need a conditional \ @@ -359,14 +343,14 @@ test: $else_allowed = (no) ..else: $code, add $clause " " - for $i in 1 to ((#$line) - 1): + for $i in (1 to (#$line - 1)): if ($i > 1): $code, add " or " $code, add ($line.$i as lua expr) $code, add " then\n " ($action as lua) $clause = "\nelseif" - if ((#"\$code") == 0): + if (#"\$code" == 0): at $body fail (" Compile error: 'if' block has an empty body. Hint: This means nothing would happen, so the 'if' block should be deleted. @@ -389,7 +373,7 @@ test: else: fail "bad switch statement" -# Switch statement +### Switch statement [if $branch_value is $body, when $branch_value is $body] all compile to: $code = (Lua "") $clause = "if" @@ -403,7 +387,7 @@ test: for $line in $body: unless - (($line.type == "Action") and ((#$line) >= 2)) and + (($line.type == "Action") and (#$line >= 2)) and $line.(#$line) is "Block" syntax tree ..: at $line fail (" @@ -411,14 +395,14 @@ test: Hint: Each line should contain expressions followed by a block, or "else" followed by a block. ") $action = $line.(#$line) - if (($line.1 == "else") and ((#$line) == 2)): + if (($line.1 == "else") and (#$line == 2)): unless $else_allowed: at $line fail (" Compile error: You can't have two 'else' blocks. Hint: Merge all of the 'else' blocks together. ") - unless ((#"\$code") > 0): + unless (#"\$code" > 0): at $line fail (" Compile error: You can't have an 'else' block without a preceding condition. Hint: If you want the code in this block to always execute, you don't need a conditional \ @@ -429,14 +413,14 @@ test: $else_allowed = (no) ..else: $code, add $clause " " - for $i in 1 to ((#$line) - 1): + for $i in (1 to (#$line - 1)): if ($i > 1): $code, add " or " $code, add "\(mangle "branch value") == " ($line.$i as lua expr) $code, add " then\n " ($action as lua) $clause = "\nelseif" - if ((#"\$code") == 0): + if (#"\$code" == 0): at $body fail (" Compile error: 'if' block has an empty body. Hint: This means nothing would happen, so the 'if' block should be deleted. @@ -450,7 +434,7 @@ test: end -- if $ is... ") -# Do/finally +### Do/finally (do $action) compiles to (" do \($action as lua) @@ -460,8 +444,8 @@ test: test: assume ((result of: return 99) == 99) -# Inline thunk: -(result of $body) compiles to "\(\(-> $body) as lua)()" +### Inline thunk: +(result of $body) compiles to "\(("Action" tree with "->" $body) as lua)()" test: $t = [1, [2, [[3], 4], 5, [[[6]]]]] $flat = [] @@ -473,7 +457,7 @@ test: $flat, add $ assume (sorted $flat) == [1, 2, 3, 4, 5, 6] -# Recurion control flow +### Recurion control flow (recurse $v on $x) compiles to Lua "table.insert(_stack_\($v as lua expr), \($x as lua expr))" @@ -487,14 +471,14 @@ test: \($body as lua) ") - if ($body has subtree \(do next)): + if ($body, contains `(do next)): $lua, add "\n ::continue::" - if ($body has subtree \(do next $var)): - $lua, add "\n \(\(---next $var ---) as lua)" + if ($body, contains ("Action" tree with "do" "next" $var)): + $lua, add "\n \(("Action" tree with "---" "next" $var "---") as lua)" $lua, add "\n end -- Recursive loop" - if ($body has subtree \(stop $var)): - $lua, add "\n \(\(---stop $var ---) as lua)" + if ($body, contains ("Action" tree with "stop" $var)): + $lua, add "\n \(("Action" tree with "---" "stop" $var "---") as lua)" $lua, add "\nend -- Recursive scope" return $lua |