Fortran Legacy Engineering Integration (.f, .f90)

@modelscript/fortran (languages/fortran) provides native GLR parsing, AST analysis, Triple Graph Grammar (TGG) synchronization, and DAE wrapping for legacy Fortran 77 and Fortran 90 computational engines.

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Supported Extensions & Standards

Extension	Standard / Format	Description
.f, .for, .f77	Fortran 77 (Fixed Form)	Column-based legacy engineering subroutines and mathematical libraries
.f90, .f95	Fortran 90 / 95 (Free Form)	Free-form modular subroutines, derived types, and array syntax

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Key Capabilities

1. WebAssembly GLR Fortran Parser

• Built on @modelscript/dsl's ahead-of-time compiled WASM GLR parser table.
• Accurately parses both fixed-form (columns 1-5 label, 6 continuation, 7-72 statements) and modern free-form source files.
• Supports subroutines, functions, COMMON blocks, EQUIVALENCE, PARAMETER, DATA statements, multidimensional array indexing, and intrinsic mathematical functions (SIN, COS, SQRT, EXP, etc.).

2. Bidirectional Triple Graph Grammar (TGG) Rules

• Features formal bidirectional graph rewriting rules (languages/fortran/src/language.ts):
  • FortranSubroutineToModelicaFunction: Maps Fortran SUBROUTINE and FUNCTION definitions to strongly typed Modelica functions.
  • FortranAssignToModelicaEquation: Transforms Fortran numerical assignment statements into declarative Modelica equality equations.

3. Direct DAE Subroutine Lowering

• Compiles Fortran continuous state derivative subroutines directly into @modelscript/runtime's DAEBuilder SoA linear memory arena.
• Enables legacy aero-propulsion, ballistics, and nuclear thermal routines to execute within modern hybrid continuous-discrete simulation solvers without manual recoding.

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Static Analysis & Modernization Linter Rules

The Fortran analyzer surfaces modernization issues and common numeric defects:

15 rules11 error3 warning1 info Run with msx lint

All severitieserrorwarninginfo

Code	Rule	Severity	Message
M4070	undeclared-variable	error	Variable '<varName>' referenced without declaration under strict typing.
M4071	uninitialized-variable	warning	Variable '<varName>' may be used before being assigned a value.
M4072	constant-division-by-zero	error	Division by constant zero detected in arithmetic expression.
M4073	storage-bounds-overflow	error	Storage array index <arrayName>(<index>) exceeds allocated capacity of <maxCapacity>.
M4074	dead-code-after-return	warning	Unreachable statements detected following unconditional RETURN.
M4075	do-loop-index-mutation	error	DO-loop index variable '<indexVar>' is modified within its loop body.
M4076	procedural-algebraic-loop	warning	Algebraic cycle detected among procedural assignments without time-step lag: <cycleStr>.
M4077	common-block-mismatch	error	COMMON block '/<blockName>/' definition conflict: <reason>.
M4078	array-dimension-underflow	error	Array '<arrName>' declared with non-positive dimension size (<dim> <= 0).
M4079	obsolete-arithmetic-if	info	Three-way arithmetic IF is obsolescent; prefer structured IF/THEN/ELSE.
M4080	identifier-mismatch	error	End <unitKind> identifier '<endName>' does not match '<startName>'.
M4081	intent-in-mutation	error	Dummy argument '<varName>' declared with 'INTENT(IN)' cannot be modified.
M4082	invalid-statement-syntax	error	Syntax error in Fortran statement: <detail>.
M4083	unclosed-block	error	Unclosed or mismatched '<blockName>' block structure.
M4084	math-domain-violation	error	Intrinsic math function '<fnName>' evaluated outside its real domain with argument '<argVal>'.

Generated from languages/fortran/src/lints/index.ts. All languages →

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CLI Usage

Fortran sources are handled by the generic workspace commands. The language is detected from the file extension (.f, .for, .f90, .f95, .f03, .f08).

# Lint legacy Fortran engineering subroutines
msx lint TurbomachineryModel.f

# Lint only the Fortran files in a mixed-language workspace
msx lint ./src --language fortran

# Print the parse tree of a Fortran source file
msx parse PropulsionAero.f90

DAE lowering is available from the package API (there is no dedicated msx fortran command yet):

import { lintFortranSource, lowerFortranToDae } from "@modelscript/fortran";

const diagnostics = lintFortranSource(source);
const result = lowerFortranToDae(builder, source.split("\n"));