Reference

This section is a comprehensive reference for the WRESL+ language. Use it to look up exact syntax, available keywords, and supported functions.

Keywords

The following keywords are recognized by the WRESL+ parser (case-insensitive):

Category	Keywords
Variable definition	define, svar, dvar, const
Variable content	value, timeseries, alias, external, std, integer, binary
Bounds	lower, upper, unbounded
Metadata	kind, units, convert
Goals/Objectives	goal, objective, lhs, rhs, penalty, constrain
Table lookups	select, from, given, use, where
Summation	sum
Conditions	condition, always, case
Logical operators	.and., .or., .not.
Control flow	if, elseif, else
Model structure	model, group, sequence, initial, include, order, timestep
Special identifiers	month, wateryear, day, daysin, daysinmonth, daysintimestep
Unit conversions	taf_cfs, cfs_taf, af_cfs, cfs_af
Calendar months	jan, feb, mar, apr, may, jun, jul, aug, sep, oct, nov, dec
Previous months	prevjan, prevfeb, …, prevdec

Variable Definition Syntax

TimeArray — An optional parenthesized integer or identifier, e.g., (12), that declares the variable as a time array with multiple slots (one per sub-timestep). When omitted, the variable holds a single value per timestep. This is used for variables that need to store values across multiple sub-periods within a timestep.

State Variable

define|svar [(TimeArray)] [[local]] Name { SvarContent }

Where SvarContent is one of:

• value Expression

• timeseries ['BPart'] kind 'K' units 'U' [convert 'C']

• select Column from Table [given Assign use ID] [where Assignments]

• sum(i=Expr1,Expr2) Expression

• One or more case Name { condition LogicalExpr|always  value|select|sum ... }

Examples:

! Source: CalSim3 DCR 9.5.0 — arcs-Inflows.wresl
define I_SHSTA {timeseries kind 'INFLOW' units 'TAF' convert 'CFS'}

! Source: CalSim3 DCR 9.5.0 — arcs-Reservoirs.wresl
define S_SHSTAlevel1 {value 550}

! Source: CalSim3 DCR 9.5.0 — arcs-Reservoirs.wresl
define A_SHSTAlast {
  select area from res_info
    given storage = 1000*S_SHSTA(-1)
    use linear
    where res_num = 4
}

! Source: WRESL+ Language Reference (2018)
svar Z {sum(i=1, 5, 1) S03(-i) + I10(-i)}

! Source: WRESL+ Language Reference (2018)
svar NMTest {
  case February {
    condition month == feb
    value S10(-12) + sumI10_part
  }
  case Others {
    condition always
    value S10(prevfeb) + sumI10_part
  }
}

Decision Variable

define|dvar [(TimeArray)] [[local]] Name { DvarContent }

Where DvarContent is one of:

• std kind 'K' units 'U'

• [lower Expr] [upper Expr] kind 'K' units 'U'

• binary kind 'K' units 'U'

• integer std kind 'K' units 'U'

• integer [lower Expr] [upper Expr] kind 'K' units 'U'

Examples:

! Source: WRESL+ Language Reference (2018)
dvar C_Delta_SWP {std kind 'FLOW-CHANNEL' units 'CFS'}
dvar QPD {lower -100. upper unbounded kind 'FLOW' units 'CFS'}
dvar Integer2 {integer lower 0 upper 3 kind 'INTEGER' units 'NA'}

Constant

const [[local]] Name { Number }

Example:

! Source: CalSim3 DCR 9.5.0 — arcs-Reservoirs.wresl
define S_SHSTAlevel1 {value 550}

Alias

define [(TimeArray)] [[local]] Name { alias Expression [kind 'K'] [units 'U'] }

Example:

! Source: CalSim3 DCR 9.5.0 — SoDeltaChannels.wresl
define OMFlow {alias C_OMR014 kind 'FLOW-CHANNEL' units 'CFS'}

! Source: WRESL+ Language Reference (2018)
alias Estlim3 {max(300., Est_rel) kind 'DEBUG' units 'CFS'}

External

define [[local]] Name { external LibraryName[.dll|.f90] }

Where LibraryName is the filename of an external DLL or Fortran 90 library. The external function is called by the evaluator at runtime.

Example:

! Source: CalSim3 DCR 9.5.0 — CVGroundwater_ExtFuncs.wresl
define InitGWSystem {EXTERNAL interfacetogw_x64.dll}

Goal Syntax

Simple goal

goal [(TimeArray)] [[local]] Name { Expression < | > | = Expression }

Examples:

! Source: CalSim3 DCR 9.5.0 — constraints-Connectivity.wresl
goal continuitySHSTA {I_SHSTA - C_SHSTA - D_SHSTA_WTPJMS - E_SHSTA = S_SHSTA * taf_cfs - S_SHSTA(-1) * taf_cfs + 0.}

! Source: WRESL+ Language Reference (2018)
goal Test {X > Y}

Complex goal with LHS/RHS

goal [(TimeArray)] [[local]] Name {
  lhs Expression
  rhs Expression
  [lhs > rhs  constrain | penalty Expression]
  [lhs < rhs  constrain | penalty Expression]
}

Example:

! Source: WRESL+ Language Reference (2018)
goal NMTest {
  lhs X + Y
  rhs Z
  lhs > rhs constrain
  lhs < rhs penalty 0
}

Complex goal with cases

goal [(TimeArray)] [[local]] Name {
  lhs Expression
  case CaseName {
    condition LogicalExpression | always
    rhs Expression
    [lhs > rhs  constrain | penalty Expression]
    [lhs < rhs  constrain | penalty Expression]
  }
  ...
}

Example:

! Source: WRESL+ Language Reference (2018)
goal TestAction1 {
  lhs D_J1 + D_B1
  case April {
    condition month == apr
    rhs CNW + X
    lhs < rhs penalty 0
  }
  case Others {
    condition always
    rhs 3000. * 16.0 / daysin + Z
    lhs < rhs penalty 0
    lhs > rhs constrain
  }
}

Objective Syntax

objective [[local]] Name [=] {
  [VarRef [(TimeArray)], WeightExpression],
  ...
}

Notes:

• For Decision Variables declared as a time array, the (TimeArray) in the objective entry must match the declaration.

• For non-time-array Decision Variables, omit the time array specifier.

Example:

! Source: WRESL+ Language Reference (2018)
objective XGroup {[X1, 10] [X2, 20]}

! Source: CalSim3 DCR 9.5.0 — Weight-table.wresl (abbreviated)
Objective obj_SYS = {
  [S_TRNTY_1, 200000*taf_cfs],
  [S_TRNTY_2, 93*taf_cfs],
  [S_SHSTA_1, 200000*taf_cfs],
  [S_SHSTA_2, 93*taf_cfs]
}

Model Structure Syntax

Sequence

sequence Name { model ModelRef [condition LogicalExpr] [order INT] [timestep 1MON|1DAY] }

Example:

! Source: WRESL+ Language Reference (2018)
sequence CYCLE1 {model Upstream order 1}
sequence CYCLE4 {model Test2 condition MON==jun order 4}

! Source: CalSim3 DCR 9.5.0 — mainCS3_ReOrg_UWplusVF.wresl
SEQUENCE CYCLE33 {model UPSTREAM condition simulateSacramentoValley >= 0.5 order 33}

Model

model Name { (Pattern | IfIncItems)+ }

Example:

! Source: CalSim3 DCR 9.5.0 — mainCS3_ReOrg_UWplusVF.wresl (abbreviated)
model UPSTREAM {
  include group Tdomain
  include group Common_All
  include 'System\System_Sac_cycle1.wresl'
  if simulateSacVA_TisdaleWeir < 0.5 {
    include 'SystemTables_Sac\constraints-Weirs2.wresl'
  }
}

Group

group Name { (Pattern | IfIncItems)+ }

Example:

! Source: CalSim3 DCR 9.5.0 — mainCS3_ReOrg_UWplusVF.wresl
group Common_All {
  include 'CVGroundwater\CalSim3GWregionIndex.wresl'
  include 'Other\NewFacilitySwitches.wresl'
  include 'Other\wytypes\WyTypesGeneral.wresl'
}

Initial

initial { (SimpleValueSvar | LookupTableSvar | IncludeStatement)+ }

Notes:

• Runs once before the main simulation loop.

• Only simple value or lookup table state variables are allowed.

• Include statements are often used to bring in files with these variables.

Example:

! Source: WRESL+ Language Reference (2018)
initial {
  svar A {value 10.}
  svar B {value A * 5}
  svar C {value B + 6.0}
}

! Source: CalSim3 DCR 9.5.0 — mainCS3_ReOrg_UWplusVF.wresl (abbreviated)
initial {
  include 'System\SystemTables_Sac\arcs-Reservoirs.wresl'
  include 'CVGroundwater\CVGroundwater_init1_SJRBASE.wresl'
}

Include

include [[local]] 'filepath.wresl'
include model ModelName
include group GroupName

Data Types

• Integer (e.g., 42, 550)

• Float (e.g., 3.14, .5, 1.98347)

Operators

Type	Operators
Arithmetic	+, -, *, /
Comparison	==, /= (not equal), <, >, <=, >=
Logical	.and., .or., .not.

Comments

Single-line comments begin with !:

! Sacramento River inflow to Shasta
define I_SHSTA {value 10000}   ! CFS

Strings

Strings use single quotes:

kind 'FLOW-CHANNEL'
units 'CFS'
include 'System\SystemTables_Sac\arcs-Reservoirs.wresl'

Supported Functions

Function	Description	Example
min(a, b, ...)	Minimum of values	min(I_SHSTA, maxCapacity)
max(a, b, ...)	Maximum of values	max(C_SHSTA, 0)
abs(x)	Absolute value	abs(S_SHSTA - target)
round(x)	Round to nearest integer	round(ratio)
int(x)	Truncate to integer	int(2.9) → 2
mod(a, b)	Modulo (remainder)	mod(month, 12)
pow(a, b)	Power (a raised to b)	pow(base, exp)
log(x)	Logarithm (also log10)	log(value)
sin(x)	Sine	sin(angle)
cos(x)	Cosine	cos(angle)
tan(x)	Tangent	tan(angle)
cot(x)	Cotangent	cot(angle)
asin(x)	Arc sine	asin(ratio)
acos(x)	Arc cosine	acos(ratio)
atan(x)	Arc tangent	atan(slope)
acot(x)	Arc cotangent	acot(value)
range(var, start, end)	Check if month/year is in range	range(month, oct, mar)

Special Built-in Identifiers

Identifier	Description
month	Current simulation month (numeric)
wateryear	Current water year
day	Current simulation day
daysin / daysinmonth	Number of days in current month
daysintimestep	Number of days in current timestep. Note: This is a built-in evaluator keyword, not a parser-level keyword. It is case-sensitive and must be written in lowercase only.
jan … dec	Calendar month constants
prevjan … prevdec	Previous year’s month references
taf_cfs	TAF to CFS conversion factor for the current timestep
cfs_taf	CFS to TAF conversion factor for the current timestep
af_cfs	AF to CFS conversion factor for the current timestep
cfs_af	CFS to AF conversion factor for the current timestep
$m	Multi-step reference
i	Loop variable (used inside sum expressions)

Variable Cross-References

Syntax	Meaning	Example
varName[modelName]	Reference variable as solved in another model cycle	C_CAA003_EXP1[WHEELJPOD]
varName(-1)	Reference variable from the previous time step	S_SHSTA(-1)
varName[modelName](offset)	Cross-model reference with time offset	EiExpCtrl[PRESETUP](-1)
varName[-1]	Index-based variable reference	S_SHSTA[-1]